Systems and methods for improving security of secure socket layer (ssl) communications

ABSTRACT

The disclosure is directed to a system for improving security of SSL communications. The system can include an device intermediary between one or more servers, one or more clients, a plurality of agents, and a web service. The servers can be configured to receive SSL connections and issue SSL certificates. The device can include a virtual server associated with a respective one of the servers, such that the SSL certificate of the respective server is transmitted through the device. The device can generate service fingerprints for the one or more servers. Each service fingerprint can include information corresponding to an SSL certificate of the virtual server, one or more DNS aliases for a virtual IP address of the respective virtual server, one or more port numbers serving the SSL certificate, and an IP address serviced by the device. The device also can transmit the service fingerprints to a web service.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of, and claims priority to andthe benefit of U.S. patent application Ser. No. 15/148,374, titled“SYSTEMS AND METHODS FOR IMPROVING SECURITY OF SECURE SOCKET LAYER (SSL)COMMUNICATIONS,” and filed May 6, 2016, which claims priority to and thebenefit of U.S. Provisional Patent Application No. 62/158,876, titled“SYSTEMS AND METHODS FOR IMPROVING SECURITY OF SECURE SOCKET LAYER (SSL)COMMUNICATIONS,” and filed May 8, 2015, the contents of all of which arehereby incorporated herein by reference in its entirety for allpurposes.

FIELD OF THE DISCLOSURE

The present application generally relates to computer networks. Inparticular, the present application relates to systems and methods forimproving security of Secure Socket Layer (SSL) communications.

BACKGROUND

Computing devices commonly use a technology known as Secure Socket Layer(SSL) for transmitting and receiving encrypted information. However,this technology can be vulnerable to attacks by third parties.

BRIEF SUMMARY

Secure Socket Layer (SSL) is a protocol designed to providecommunications security over a computer network. When a client deviceattempts to establish an SSL connection with a server, the server issuesan SSL certificate to the client device. Typically an SSL certificateincludes information such as the domain name, company name, and addressof the organization that owns the server. SSL certificates are issued toorganizations by a certificate authority, which should take steps toconfirm the identity of the organization applying for the certificate.Therefore, receipt of an SSL certificate is intended to provide somedegree of assurance to a client device that the server to which theclient has requested a connection is owned by a trusted organization.

Because SSL certificates are issued by certificate authorities, an SSLcertificate is only as secure as the certificate authority itself. Forexample, in some instances, a certificate authority may knowingly issuea valid certificate to the wrong party. In other instances, acertificate authority may be deceived into issuing a valid certificateto a malicious party who is impersonating a trusted organization.Therefore, mere receipt of a valid SSL certificate by a client devicecannot guarantee that the server to which the client has requested aconnection is actually owned by a trusted organization.

Furthermore, SSL communications also can be compromised by other typesof attacks. For example, in a man-in-the-middle (MITM) attack, a thirdparty intercepts communications sent from a client device to a serverand also intercepts communications sent from the server to the clientdevice. The third party impersonates the server to the client device,and impersonates the client device to the server, thereby accessing allof the information transmitted over the connection without the knowledgeof either of the client device or the server.

Thus, the certificate trust model underpinning SSL communication can beunreliable. The present disclosure provides methods and systems forimproving security of SSL communications. SSL Security can be improved,for example, by verifying that a server issuing an SSL certificateresponds using an expected SSL certificate, indicating that thecertificate has not been forged, and by verifying that the connection tothe server resolves to the expected internet protocol (IP) address,indicating that the private key has not been stolen. In someimplementations, additional protective measures also may be taken. Forexample, SSL certificates can be analyzed to determine whether thecertificates correspond to up-to-date best practices in computersecurity. Other networking functions, such as border gateway protocol(BGP), also can be analyzed to provide additional measures of security.

In some implementations of the present disclosure, a device intermediarybetween a plurality of clients and a plurality of servers cancommunicate with a web server. The device can, for each virtual serverwith a configured SSL certificate, communicate one or more servicefingerprints to the web service. The service fingerprint can include theDomain Name Service (DNS) aliases for the virtual IP address of thevirtual server, one or more port numbers serving the SSL certificate,the IP address serviced by the device and the certificate being served.In some implementations, the service fingerprint does not include theprivate key corresponding to the SSL certificate.

The web service can combine this information from one or more devicesowned by a customer associated with the SSL certificate to construct afull set of mappings for which the SSL certificate should be issued byany particular Internet-facing virtual server. The web service canmanage, maintain or own a set of agents distributed over multipleservice provider networks globally that periodically connect to eachknown virtual server, and report if the DNS-to-IP mapping or SSLcertificate were not those anticipated. Upon collating these results,the web service then notifies the administrator of the device that theirvirtual server seems to be under attack. As the device is reconfiguredover time (such as to replace expiring SSL certificates, or to service anew IP or DNS name), the device can automatically propagate the newservice fingerprint to the web service.

In one aspect, the present disclosure is directed to a system forimproving security of SSL communications. The system can include andevice intermediary between one or more servers, one or more clients, aplurality of agents, and a web service. The servers can be configured toreceive SSL connections and issue SSL certificates. The intermediarydevice can include a virtual server associated with a respective one ofthe servers, such that the SSL certificate of the respective server istransmitted through the intermediary device. The intermediary device canbe configured to generate service fingerprints for the one or moreservers. Each service fingerprint can include information correspondingto an SSL certificate of the respective virtual server, one or more DNSaliases for a virtual IP address of the respective virtual server, oneor more port numbers serving the SSL certificate, and an IP addressserviced by the device. The intermediary device also can be configuredto transmit the service fingerprints to a web service. The agents can beconfigured to attempt to establish SSL connections to at least one ofthe virtual servers and to receive an SSL certificate in response. Theweb service can be configured to receive, from at least one agent,information corresponding to the SSL certificate and the IP address fromwhich the SSL certificate was received by the agent. The web servicealso can be configured to determine that a virtual server iscompromised, based on a mismatch between the respective service mappingof the at least one virtual server and the received SSL certificate orthe IP address from which the SSL certificate was received by the agent.

In some implementations, the intermediary device may generate a uniqueverification key that can be included in the service fingerprint. Thisverification key can then be checked by the agents via a privateextension to the SSL handshake to enable greater confidence that the SSLendpoint is in fact the server. In some implementations, the agents maycollect additional information relevant to understanding the nature of apotential attack. For example, the output of a “traceroute” commandperformed on data transmitted over an established SSL connection canprovide additional information regarding the likely connection pathaffected by an attack. In some implementations, the web service maycollect feeds of SSL certificates issued or revoked from certificateauthorities as an additional source indicating whether the SSLcertificate of the server 709 has been compromised. In someimplementations, the web service may monitor additional protocols, suchas the border gateway protocol (BGP), to detect whether the virtualserver corresponding to the server has been compromised by a malicioustraffic route. In some implementations, the web service may periodicallycheck all known certificates against evolving industry best practices,such as key length, padding, and crypto algorithms, to determine whetheran SSL certificate no longer follows up-to-date best practices.

In another aspect, the present disclosure is directed to a method forimproving security of SSL communications. The method can includegenerating one or more service fingerprints for one or more virtualservers. Each service fingerprint can include information correspondingto an SSL certificate of the respective virtual server, one or more DNSaliases for a virtual IP address of the respective virtual server, oneor more port numbers serving the SSL certificate, and an IP addressserviced by the device. The method can include creating a servicemapping of SSL certificates and virtual servers, based on the one ormore service fingerprints. The method can include attempting toestablish an SSL connection to at least one of the virtual servers toreceive an SSL certificate. The method can include determining that theat least one virtual server is compromised, based on a mismatch betweenthe respective service mapping of the at least one virtual server andthe received SSL certificate or the IP address from which the SSLcertificate was received.

In another aspect, the present disclosure is directed to a method forimproving security of SSL communication. The method can includedetermining, by a device intermediary to a plurality of clients and oneor more servers, a configuration change associated with a virtual serverexecuting on the device. The method can include generating, by thedevice, responsive to determining the configuration change associatedwith the virtual server, a service fingerprint for the virtual server.The service fingerprint can include a DNS alias for a virtual IP addressof the virtual server, a port number of the virtual server serving anSSL certificate of the virtual server, an IP address serviced by thedevice, and the SSL certificate. The method can include transmitting, bythe device, the generated service fingerprint to a web service tocompare the generated service fingerprint with data received by the webservice from an agent to identify that the device is under attack.

In some implementations, the method can include receiving, by the devicefrom the web service, a notification that the device is under attack,responsive to the web service determining that i) the SSL certificatedoes not match a second SSL certificate received from an agent thatattempted to establish a secure connection with the virtual server, orii) that the IP address of the virtual server does not match a second IPaddress received from the agent. In some implementations, thenotification indicates that the attack is a man-in-the-middle (MITM)attack.

In some implementations, determining the configuration change associatedwith the virtual server comprises determining, by the device, that theSSL certificate of the virtual server has replaced an expired SSLcertificate of the virtual server. In some implementations, determiningthe configuration change associated with the virtual server comprisesdetermining, by the device, that the virtual server is associated with anew IP address not previously serviced by the virtual server. In someimplementations, determining the configuration change associated withthe virtual server comprises determining, by the device, that thevirtual server services a new DNS name not previously serviced by thevirtual server.

In some implementations, the service fingerprint does not include aprivate key corresponding to the SSL certificate. In someimplementations, the method can include generating, by the device, aunique verification key to allow the virtual server to implement aprivate extension of an SSL handshake when the SSL certificate is servedbased on the unique verification key. In some implementations,generating the service fingerprint further comprises generating, by thedevice, the service fingerprint including the unique verification key.In some implementations, the method includes receiving, from an agent, arequest to establish a secure connection between the agent and thevirtual server and transmitting, by the device, the SSL certificate andthe unique verification key to the agent, responsive to receiving therequest to establish the secure connection.

In another aspect, the present disclosure is directed to a system forimproving security of SSL communication. The system can include a deviceintermediary to a plurality of clients and one or more servers. Thedevice can include a configuration change identifier configured todetermine a configuration change associated with a virtual serverexecuting on the device. The device can include a service fingerprintgenerator configured to generate, responsive to determining theconfiguration change associated with the virtual server, a servicefingerprint for the virtual server. The service fingerprint can includea DNS alias for a virtual IP address of the virtual server, a portnumber of the virtual server serving an SSL certificate of the virtualserver, an IP address of the virtual server, and the SSL certificate.The device also can include a service fingerprint transmitter configuredto transmit the generated service fingerprint to a web service tocompare the generated service fingerprint with data received by the webservice from an agent to identify that the device is under attack.

In some implementations, the device can include a notification receiverconfigured to receive, from the web service, a notification that thedevice is under attack, responsive to the web service determining thati) the SSL certificate does not match a second SSL certificate receivedfrom an agent that attempted to establish a secure connection with thevirtual server, or ii) that the IP address of the virtual server doesnot match a second IP address received from the agent.

In some implementations, the notification indicates that the attack is aman-in-the-middle (MITM) attack. In some implementations, theconfiguration change identifier is further configured to determine thatthe SSL certificate of the virtual server has replaced an expired SSLcertificate of the virtual server. In some implementations, theconfiguration change identifier is further configured to determine thatthe virtual server is associated with a new IP address not previouslyserviced by the virtual server. In some implementations, theconfiguration change identifier is further configured to determine thatthe virtual server services a new DNS name not previously serviced bythe virtual server.

In some implementations, the service fingerprint does not include aprivate key corresponding to the SSL certificate. In someimplementations, the device further comprises a verification keygenerator configured to generate a unique verification key to allow thevirtual server to implement a private extension of an SSL handshake whenthe SSL certificate is served based on the unique verification key. Insome implementations, the service fingerprint generator is furtherconfigured to generate the service fingerprint to include the uniqueverification key.

In some implementations, the device further comprises a secureconnection interface configured to receive, from an agent, a request toestablish a secure connection between the agent and the virtual serverand transmit the SSL certificate and the unique verification key to theagent, responsive to receiving the request to establish the secureconnection.

The details of various embodiments of the invention are set forth in theaccompanying drawings and the description below.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other objects, aspects, features, and advantages ofthe invention will become more apparent and better understood byreferring to the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a block diagram of an embodiment of a network environment fora client to access a server via an appliance;

FIG. 1B is a block diagram of an embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIG. 1C is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIG. 1D is a block diagram of another embodiment of an environment fordelivering a computing environment from a server to a client via anappliance;

FIGS. 1E-1H are block diagrams of embodiments of a computing device;

FIG. 2A is a block diagram of an embodiment of an appliance forprocessing communications between a client and a server;

FIG. 2B is a block diagram of another embodiment of an appliance foroptimizing, accelerating, load-balancing and routing communicationsbetween a client and a server;

FIG. 3 is a block diagram of an embodiment of a client for communicatingwith a server via the appliance;

FIG. 4A is a block diagram of an embodiment of a virtualizationenvironment;

FIG. 4B is a block diagram of another embodiment of a virtualizationenvironment;

FIG. 4C is a block diagram of an embodiment of a virtualized appliance;

FIG. 5A are block diagrams of embodiments of approaches to implementingparallelism in a multi-core system;

FIG. 5B is a block diagram of an embodiment of a system utilizing amulti-core system;

FIG. 5C is a block diagram of another embodiment of an aspect of amulti-core system;

FIG. 6 is a block diagram of an embodiment of a cluster system;

FIG. 7A is a block diagram of an embodiment of a system for improvingsecurity of SSL communications;

FIG. 7B is a block diagram of an embodiment of an intermediary deviceincluded in the system shown in FIG. 7A;

FIG. 7C is a flow chart of an embodiment of a first method for improvingsecurity of SSL communications; and

FIG. 7D is a flow chart of an embodiment of a second method forimproving security of SSL communications.

The features and advantages of the present invention will become moreapparent from the detailed description set forth below when taken inconjunction with the drawings, in which like reference charactersidentify corresponding elements throughout. In the drawings, likereference numbers generally indicate identical, functionally similar,and/or structurally similar elements.

DETAILED DESCRIPTION

For purposes of reading the description of the various embodimentsbelow, the following descriptions of the sections of the specificationand their respective contents may be helpful:

-   -   Section A describes a network environment and computing        environment which may be useful for practicing embodiments        described herein;    -   Section B describes embodiments of systems and methods for        delivering a computing environment to a remote user;    -   Section C describes embodiments of systems and methods for        accelerating communications between a client and a server;    -   Section D describes embodiments of systems and methods for        virtualizing an application delivery controller;    -   Section E describes embodiments of systems and methods for        providing a multi-core architecture and environment;    -   Section F describes embodiments of systems and methods for        providing a clustered appliance architecture environment; and    -   Section G describes embodiments of systems and methods for        improving security of SSL communications.

A. Network and Computing Environment

Prior to discussing the specifics of embodiments of the systems andmethods of an appliance and/or client, it may be helpful to discuss thenetwork and computing environments in which such embodiments may bedeployed. Referring now to FIG. 1A, an embodiment of a networkenvironment is depicted. In brief overview, the network environmentcomprises one or more clients 102 a-102 n (also generally referred to aslocal machine(s) 102, or client(s) 102) in communication with one ormore servers 106 a-106 n (also generally referred to as server(s) 106,or remote machine(s) 106) via one or more networks 104, 104′ (generallyreferred to as network 104). In some embodiments, a client 102communicates with a server 106 via an appliance 200.

Although FIG. 1A shows a network 104 and a network 104′ between theclients 102 and the servers 106, the clients 102 and the servers 106 maybe on the same network 104. The networks 104 and 104′ can be the sametype of network or different types of networks. The network 104 and/orthe network 104′ can be a local-area network (LAN), such as a companyIntranet, a metropolitan area network (MAN), or a wide area network(WAN), such as the Internet or the World Wide Web. In one embodiment,network 104′ may be a private network and network 104 may be a publicnetwork. In some embodiments, network 104 may be a private network andnetwork 104′ a public network. In another embodiment, networks 104 and104′ may both be private networks. In some embodiments, clients 102 maybe located at a branch office of a corporate enterprise communicatingvia a WAN connection over the network 104 to the servers 106 located ata corporate data center.

The network 104 and/or 104′ be any type and/or form of network and mayinclude any of the following: a point to point network, a broadcastnetwork, a wide area network, a local area network, a telecommunicationsnetwork, a data communication network, a computer network, an ATM(Asynchronous Transfer Mode) network, a SONET (Synchronous OpticalNetwork) network, a SDH (Synchronous Digital Hierarchy) network, awireless network and a wireline network. In some embodiments, thenetwork 104 may comprise a wireless link, such as an infrared channel orsatellite band. The topology of the network 104 and/or 104′ may be abus, star, or ring network topology. The network 104 and/or 104′ andnetwork topology may be of any such network or network topology as knownto those ordinarily skilled in the art capable of supporting theoperations described herein.

As shown in FIG. 1A, the appliance 200, which also may be referred to asan interface unit 200 or gateway 200, is shown between the networks 104and 104′. In some embodiments, the appliance 200 may be located onnetwork 104. For example, a branch office of a corporate enterprise maydeploy an appliance 200 at the branch office. In other embodiments, theappliance 200 may be located on network 104′. For example, an appliance200 may be located at a corporate data center. In yet anotherembodiment, a plurality of appliances 200 may be deployed on network104. In some embodiments, e.g., as shown in FIGS. 1A-1D, a plurality ofappliances 200 may be deployed on network 104′. In one embodiment, afirst appliance 200 communicates with a second appliance 200′. In otherembodiments, the appliance 200 could be a part of any client 102 orserver 106 on the same or different network 104,104′ as the client 102.One or more appliances 200 may be located at any point in the network ornetwork communications path between a client 102 and a server 106.

In some embodiments, the appliance 200 comprises any of the networkdevices manufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla.,referred to as Citrix NetScaler devices. In other embodiments, theappliance 200 includes any of the product embodiments referred to asWebAccelerator and BigIP manufactured by F5 Networks, Inc. of Seattle,Wash. In another embodiment, the appliance 205 includes any of the DXacceleration device platforms and/or the SSL VPN series of devices, suchas SA 700, SA 2000, SA 4000, and SA 6000 devices manufactured by JuniperNetworks, Inc. of Sunnyvale, Calif. In yet another embodiment, theappliance 200 includes any application acceleration and/or securityrelated appliances and/or software manufactured by Cisco Systems, Inc.of San Jose, Calif., such as the Cisco ACE Application Control EngineModule service software and network modules, and Cisco AVS SeriesApplication Velocity System.

In one embodiment, the system may include multiple, logically-groupedservers 106. In these embodiments, the logical group of servers may bereferred to as a server farm 38. In some of these embodiments, theserves 106 may be geographically dispersed. In some cases, a farm 38 maybe administered as a single entity. In other embodiments, the serverfarm 38 comprises a plurality of server farms 38. In one embodiment, theserver farm executes one or more applications on behalf of one or moreclients 102.

The servers 106 within each farm 38 can be heterogeneous. One or more ofthe servers 106 can operate according to one type of operating systemplatform (e.g., WINDOWS NT, manufactured by Microsoft Corp. of Redmond,Wash.), while one or more of the other servers 106 can operate onaccording to another type of operating system platform (e.g., Unix orLinux). The servers 106 of each farm 38 do not need to be physicallyproximate to another server 106 in the same farm 38. Thus, the group ofservers 106 logically grouped as a farm 38 may be interconnected using awide-area network (WAN) connection or medium-area network (MAN)connection. For example, a farm 38 may include servers 106 physicallylocated in different continents or different regions of a continent,country, state, city, campus, or room. Data transmission speeds betweenservers 106 in the farm 38 can be increased if the servers 106 areconnected using a local-area network (LAN) connection or some form ofdirect connection.

Servers 106 may be referred to as a file server, application server, webserver, proxy server, or gateway server. In some embodiments, a server106 may have the capacity to function as either an application server oras a master application server. In one embodiment, a server 106 mayinclude an Active Directory. The clients 102 may also be referred to asclient nodes or endpoints. In some embodiments, a client 102 has thecapacity to function as both a client node seeking access toapplications on a server and as an application server providing accessto hosted applications for other clients 102 a-102 n.

In some embodiments, a client 102 communicates with a server 106. In oneembodiment, the client 102 communicates directly with one of the servers106 in a farm 38. In another embodiment, the client 102 executes aprogram neighborhood application to communicate with a server 106 in afarm 38. In still another embodiment, the server 106 provides thefunctionality of a master node. In some embodiments, the client 102communicates with the server 106 in the farm 38 through a network 104.Over the network 104, the client 102 can, for example, request executionof various applications hosted by the servers 106 a-106 n in the farm 38and receive output of the results of the application execution fordisplay. In some embodiments, only the master node provides thefunctionality required to identify and provide address informationassociated with a server 106′ hosting a requested application.

In one embodiment, the server 106 provides functionality of a webserver. In another embodiment, the server 106 a receives requests fromthe client 102, forwards the requests to a second server 106 b andresponds to the request by the client 102 with a response to the requestfrom the server 106 b. In still another embodiment, the server 106acquires an enumeration of applications available to the client 102 andaddress information associated with a server 106 hosting an applicationidentified by the enumeration of applications. In yet anotherembodiment, the server 106 presents the response to the request to theclient 102 using a web interface. In one embodiment, the client 102communicates directly with the server 106 to access the identifiedapplication. In another embodiment, the client 102 receives applicationoutput data, such as display data, generated by an execution of theidentified application on the server 106.

Referring now to FIG. 1B, an embodiment of a network environmentdeploying multiple appliances 200 is depicted. A first appliance 200 maybe deployed on a first network 104 and a second appliance 200′ on asecond network 104′. For example a corporate enterprise may deploy afirst appliance 200 at a branch office and a second appliance 200′ at adata center. In another embodiment, the first appliance 200 and secondappliance 200′ are deployed on the same network 104 or network 104. Forexample, a first appliance 200 may be deployed for a first server farm38, and a second appliance 200 may be deployed for a second server farm38′. In another example, a first appliance 200 may be deployed at afirst branch office while the second appliance 200′ is deployed at asecond branch office'. In some embodiments, the first appliance 200 andsecond appliance 200′ work in cooperation or in conjunction with eachother to accelerate network traffic or the delivery of application anddata between a client and a server

Referring now to FIG. 1C, another embodiment of a network environmentdeploying the appliance 200 with one or more other types of appliances,such as between one or more WAN optimization appliance 205, 205′ isdepicted. For example a first WAN optimization appliance 205 is shownbetween networks 104 and 104′ and a second WAN optimization appliance205′ may be deployed between the appliance 200 and one or more servers106. By way of example, a corporate enterprise may deploy a first WANoptimization appliance 205 at a branch office and a second WANoptimization appliance 205′ at a data center. In some embodiments, theappliance 205 may be located on network 104′. In other embodiments, theappliance 205′ may be located on network 104. In some embodiments, theappliance 205′ may be located on network 104′ or network 104″. In oneembodiment, the appliance 205 and 205′ are on the same network. Inanother embodiment, the appliance 205 and 205′ are on differentnetworks. In another example, a first WAN optimization appliance 205 maybe deployed for a first server farm 38 and a second WAN optimizationappliance 205′ for a second server farm 38′

In one embodiment, the appliance 205 is a device for accelerating,optimizing or otherwise improving the performance, operation, or qualityof service of any type and form of network traffic, such as traffic toand/or from a WAN connection. In some embodiments, the appliance 205 isa performance enhancing proxy. In other embodiments, the appliance 205is any type and form of WAN optimization or acceleration device,sometimes also referred to as a WAN optimization controller. In oneembodiment, the appliance 205 is any of the product embodiments referredto as WANScaler manufactured by Citrix Systems, Inc. of Ft. Lauderdale,Fla. In other embodiments, the appliance 205 includes any of the productembodiments referred to as BIG-IP link controller and WANjetmanufactured by F5 Networks, Inc. of Seattle, Wash. In anotherembodiment, the appliance 205 includes any of the WX and WXC WANacceleration device platforms manufactured by Juniper Networks, Inc. ofSunnyvale, Calif. In some embodiments, the appliance 205 includes any ofthe steelhead line of WAN optimization appliances manufactured byRiverbed Technology of San Francisco, Calif. In other embodiments, theappliance 205 includes any of the WAN related devices manufactured byExpand Networks Inc. of Roseland, N.J. In one embodiment, the appliance205 includes any of the WAN related appliances manufactured by PacketeerInc. of Cupertino, Calif., such as the PacketShaper, iShared, and SkyXproduct embodiments provided by Packeteer. In yet another embodiment,the appliance 205 includes any WAN related appliances and/or softwaremanufactured by Cisco Systems, Inc. of San Jose, Calif., such as theCisco Wide Area Network Application Services software and networkmodules, and Wide Area Network engine appliances.

In one embodiment, the appliance 205 provides application and dataacceleration services for branch-office or remote offices. In oneembodiment, the appliance 205 includes optimization of Wide Area FileServices (WAFS). In another embodiment, the appliance 205 acceleratesthe delivery of files, such as via the Common Internet File System(CIFS) protocol. In other embodiments, the appliance 205 providescaching in memory and/or storage to accelerate delivery of applicationsand data. In one embodiment, the appliance 205 provides compression ofnetwork traffic at any level of the network stack or at any protocol ornetwork layer. In another embodiment, the appliance 205 providestransport layer protocol optimizations, flow control, performanceenhancements or modifications and/or management to accelerate deliveryof applications and data over a WAN connection. For example, in oneembodiment, the appliance 205 provides Transport Control Protocol (TCP)optimizations. In other embodiments, the appliance 205 providesoptimizations, flow control, performance enhancements or modificationsand/or management for any session or application layer protocol.

In another embodiment, the appliance 205 encoded any type and form ofdata or information into custom or standard TCP and/or IP header fieldsor option fields of network packet to announce presence, functionalityor capability to another appliance 205′. In another embodiment, anappliance 205′ may communicate with another appliance 205′ using dataencoded in both TCP and/or IP header fields or options. For example, theappliance may use TCP option(s) or IP header fields or options tocommunicate one or more parameters to be used by the appliances 205,205′ in performing functionality, such as WAN acceleration, or forworking in conjunction with each other.

In some embodiments, the appliance 200 preserves any of the informationencoded in TCP and/or IP header and/or option fields communicatedbetween appliances 205 and 205′. For example, the appliance 200 mayterminate a transport layer connection traversing the appliance 200,such as a transport layer connection from between a client and a servertraversing appliances 205 and 205′. In one embodiment, the appliance 200identifies and preserves any encoded information in a transport layerpacket transmitted by a first appliance 205 via a first transport layerconnection and communicates a transport layer packet with the encodedinformation to a second appliance 205′ via a second transport layerconnection.

Referring now to FIG. 1D, a network environment for delivering and/oroperating a computing environment on a client 102 is depicted. In someembodiments, a server 106 includes an application delivery system 190for delivering a computing environment or an application and/or datafile to one or more clients 102. In brief overview, a client 102 is incommunication with a server 106 via network 104, 104′ and appliance 200.For example, the client 102 may reside in a remote office of a company,e.g., a branch office, and the server 106 may reside at a corporate datacenter. The client 102 comprises a client agent 120, and a computingenvironment 15. The computing environment 15 may execute or operate anapplication that accesses, processes or uses a data file. The computingenvironment 15, application and/or data file may be delivered via theappliance 200 and/or the server 106.

In some embodiments, the appliance 200 accelerates delivery of acomputing environment 15, or any portion thereof, to a client 102. Inone embodiment, the appliance 200 accelerates the delivery of thecomputing environment 15 by the application delivery system 190. Forexample, the embodiments described herein may be used to acceleratedelivery of a streaming application and data file processable by theapplication from a central corporate data center to a remote userlocation, such as a branch office of the company. In another embodiment,the appliance 200 accelerates transport layer traffic between a client102 and a server 106. The appliance 200 may provide accelerationtechniques for accelerating any transport layer payload from a server106 to a client 102, such as: 1) transport layer connection pooling, 2)transport layer connection multiplexing, 3) transport control protocolbuffering, 4) compression and 5) caching. In some embodiments, theappliance 200 provides load balancing of servers 106 in responding torequests from clients 102. In other embodiments, the appliance 200 actsas a proxy or access server to provide access to the one or more servers106. In another embodiment, the appliance 200 provides a secure virtualprivate network connection from a first network 104 of the client 102 tothe second network 104′ of the server 106, such as an SSL VPNconnection. It yet other embodiments, the appliance 200 providesapplication firewall security, control and management of the connectionand communications between a client 102 and a server 106.

In some embodiments, the application delivery management system 190provides application delivery techniques to deliver a computingenvironment to a desktop of a user, remote or otherwise, based on aplurality of execution methods and based on any authentication andauthorization policies applied via a policy engine 195. With thesetechniques, a remote user may obtain a computing environment and accessto server stored applications and data files from any network connecteddevice 100. In one embodiment, the application delivery system 190 mayreside or execute on a server 106. In another embodiment, theapplication delivery system 190 may reside or execute on a plurality ofservers 106 a-106 n. In some embodiments, the application deliverysystem 190 may execute in a server farm 38. In one embodiment, theserver 106 executing the application delivery system 190 may also storeor provide the application and data file. In another embodiment, a firstset of one or more servers 106 may execute the application deliverysystem 190, and a different server 106 n may store or provide theapplication and data file. In some embodiments, each of the applicationdelivery system 190, the application, and data file may reside or belocated on different servers. In yet another embodiment, any portion ofthe application delivery system 190 may reside, execute or be stored onor distributed to the appliance 200, or a plurality of appliances.

The client 102 may include a computing environment 15 for executing anapplication that uses or processes a data file. The client 102 vianetworks 104, 104′ and appliance 200 may request an application and datafile from the server 106. In one embodiment, the appliance 200 mayforward a request from the client 102 to the server 106. For example,the client 102 may not have the application and data file stored oraccessible locally. In response to the request, the application deliverysystem 190 and/or server 106 may deliver the application and data fileto the client 102. For example, in one embodiment, the server 106 maytransmit the application as an application stream to operate incomputing environment 15 on client 102.

In some embodiments, the application delivery system 190 comprises anyportion of the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™ and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application delivery system 190 may deliver one ormore applications to clients 102 or users via a remote-display protocolor otherwise via remote-based or server-based computing. In anotherembodiment, the application delivery system 190 may deliver one or moreapplications to clients or users via steaming of the application.

In one embodiment, the application delivery system 190 includes a policyengine 195 for controlling and managing the access to, selection ofapplication execution methods and the delivery of applications. In someembodiments, the policy engine 195 determines the one or moreapplications a user or client 102 may access. In another embodiment, thepolicy engine 195 determines how the application should be delivered tothe user or client 102, e.g., the method of execution. In someembodiments, the application delivery system 190 provides a plurality ofdelivery techniques from which to select a method of applicationexecution, such as a server-based computing, streaming or delivering theapplication locally to the client 120 for local execution.

In one embodiment, a client 102 requests execution of an applicationprogram and the application delivery system 190 comprising a server 106selects a method of executing the application program. In someembodiments, the server 106 receives credentials from the client 102. Inanother embodiment, the server 106 receives a request for an enumerationof available applications from the client 102. In one embodiment, inresponse to the request or receipt of credentials, the applicationdelivery system 190 enumerates a plurality of application programsavailable to the client 102. The application delivery system 190receives a request to execute an enumerated application. The applicationdelivery system 190 selects one of a predetermined number of methods forexecuting the enumerated application, for example, responsive to apolicy of a policy engine. The application delivery system 190 mayselect a method of execution of the application enabling the client 102to receive application-output data generated by execution of theapplication program on a server 106. The application delivery system 190may select a method of execution of the application enabling the localmachine 10 to execute the application program locally after retrieving aplurality of application files comprising the application. In yetanother embodiment, the application delivery system 190 may select amethod of execution of the application to stream the application via thenetwork 104 to the client 102.

A client 102 may execute, operate or otherwise provide an application,which can be any type and/or form of software, program, or executableinstructions such as any type and/or form of web browser, web-basedclient, client-server application, a thin-client computing client, anActiveX control, or a Java applet, or any other type and/or form ofexecutable instructions capable of executing on client 102. In someembodiments, the application may be a server-based or a remote-basedapplication executed on behalf of the client 102 on a server 106. In oneembodiments the server 106 may display output to the client 102 usingany thin-client or remote-display protocol, such as the IndependentComputing Architecture (ICA) protocol manufactured by Citrix Systems,Inc. of Ft. Lauderdale, Fla. or the Remote Desktop Protocol (RDP)manufactured by the Microsoft Corporation of Redmond, Wash. Theapplication can use any type of protocol and it can be, for example, anHTTP client, an FTP client, an Oscar client, or a Telnet client. Inother embodiments, the application comprises any type of softwarerelated to VoIP communications, such as a soft IP telephone. In furtherembodiments, the application comprises any application related toreal-time data communications, such as applications for streaming videoand/or audio.

In some embodiments, the server 106 or a server farm 38 may be runningone or more applications, such as an application providing a thin-clientcomputing or remote display presentation application. In one embodiment,the server 106 or server farm 38 executes as an application, any portionof the Citrix Access Suite™ by Citrix Systems, Inc., such as theMetaFrame or Citrix Presentation Server™, and/or any of the Microsoft®Windows Terminal Services manufactured by the Microsoft Corporation. Inone embodiment, the application is an ICA client, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla. In other embodiments, theapplication includes a Remote Desktop (RDP) client, developed byMicrosoft Corporation of Redmond, Wash. Also, the server 106 may run anapplication, which for example, may be an application server providingemail services such as Microsoft Exchange manufactured by the MicrosoftCorporation of Redmond, Wash., a web or Internet server, or a desktopsharing server, or a collaboration server. In some embodiments, any ofthe applications may comprise any type of hosted service or products,such as GoToMeeting™ provided by Citrix Online Division, Inc. of SantaBarbara, Calif., WebEx™ provided by WebEx, Inc. of Santa Clara, Calif.,or Microsoft Office Live Meeting provided by Microsoft Corporation ofRedmond, Wash.

Still referring to FIG. 1D, an embodiment of the network environment mayinclude a monitoring server 106A. The monitoring server 106A may includeany type and form performance monitoring service 198. The performancemonitoring service 198 may include monitoring, measurement and/ormanagement software and/or hardware, including data collection,aggregation, analysis, management and reporting. In one embodiment, theperformance monitoring service 198 includes one or more monitoringagents 197. The monitoring agent 197 includes any software, hardware orcombination thereof for performing monitoring, measurement and datacollection activities on a device, such as a client 102, server 106 oran appliance 200, 205. In some embodiments, the monitoring agent 197includes any type and form of script, such as Visual Basic script, orJavascript. In one embodiment, the monitoring agent 197 executestransparently to any application and/or user of the device. In someembodiments, the monitoring agent 197 is installed and operatedunobtrusively to the application or client. In yet another embodiment,the monitoring agent 197 is installed and operated without anyinstrumentation for the application or device.

In some embodiments, the monitoring agent 197 monitors, measures andcollects data on a predetermined frequency. In other embodiments, themonitoring agent 197 monitors, measures and collects data based upondetection of any type and form of event. For example, the monitoringagent 197 may collect data upon detection of a request for a web page orreceipt of an HTTP response. In another example, the monitoring agent197 may collect data upon detection of any user input events, such as amouse click. The monitoring agent 197 may report or provide anymonitored, measured or collected data to the monitoring service 198. Inone embodiment, the monitoring agent 197 transmits information to themonitoring service 198 according to a schedule or a predeterminedfrequency. In another embodiment, the monitoring agent 197 transmitsinformation to the monitoring service 198 upon detection of an event.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of any networkresource or network infrastructure element, such as a client, server,server farm, appliance 200, appliance 205, or network connection. In oneembodiment, the monitoring service 198 and/or monitoring agent 197performs monitoring and performance measurement of any transport layerconnection, such as a TCP or UDP connection. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresnetwork latency. In yet one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures bandwidth utilization.

In other embodiments, the monitoring service 198 and/or monitoring agent197 monitors and measures end-user response times. In some embodiments,the monitoring service 198 performs monitoring and performancemeasurement of an application. In another embodiment, the monitoringservice 198 and/or monitoring agent 197 performs monitoring andperformance measurement of any session or connection to the application.In one embodiment, the monitoring service 198 and/or monitoring agent197 monitors and measures performance of a browser. In anotherembodiment, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of HTTP based transactions. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of a Voice over IP (VoIP) applicationor session. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of a remotedisplay protocol application, such as an ICA client or RDP client. Inyet another embodiment, the monitoring service 198 and/or monitoringagent 197 monitors and measures performance of any type and form ofstreaming media. In still a further embodiment, the monitoring service198 and/or monitoring agent 197 monitors and measures performance of ahosted application or a Software-As-A-Service (SaaS) delivery model.

In some embodiments, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of one or moretransactions, requests or responses related to application. In otherembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures any portion of an application layer stack, such asany .NET or J2EE calls. In one embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures database or SQLtransactions. In yet another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures any method, functionor application programming interface (API) call.

In one embodiment, the monitoring service 198 and/or monitoring agent197 performs monitoring and performance measurement of a delivery ofapplication and/or data from a server to a client via one or moreappliances, such as appliance 200 and/or appliance 205. In someembodiments, the monitoring service 198 and/or monitoring agent 197monitors and measures performance of delivery of a virtualizedapplication. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors and measures performance of delivery of astreaming application. In another embodiment, the monitoring service 198and/or monitoring agent 197 monitors and measures performance ofdelivery of a desktop application to a client and/or the execution ofthe desktop application on the client. In another embodiment, themonitoring service 198 and/or monitoring agent 197 monitors and measuresperformance of a client/server application.

In one embodiment, the monitoring service 198 and/or monitoring agent197 is designed and constructed to provide application performancemanagement for the application delivery system 190. For example, themonitoring service 198 and/or monitoring agent 197 may monitor, measureand manage the performance of the delivery of applications via theCitrix Presentation Server. In this example, the monitoring service 198and/or monitoring agent 197 monitors individual ICA sessions. Themonitoring service 198 and/or monitoring agent 197 may measure the totaland per session system resource usage, as well as application andnetworking performance. The monitoring service 198 and/or monitoringagent 197 may identify the active servers for a given user and/or usersession. In some embodiments, the monitoring service 198 and/ormonitoring agent 197 monitors back-end connections between theapplication delivery system 190 and an application and/or databaseserver. The monitoring service 198 and/or monitoring agent 197 maymeasure network latency, delay and volume per user-session or ICAsession.

In some embodiments, the monitoring service 198 and/or monitoring agent197 measures and monitors memory usage for the application deliverysystem 190, such as total memory usage, per user session and/or perprocess. In other embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors CPU usage the applicationdelivery system 190, such as total CPU usage, per user session and/orper process. In another embodiments, the monitoring service 198 and/ormonitoring agent 197 measures and monitors the time required to log-into an application, a server, or the application delivery system, such asCitrix Presentation Server. In one embodiment, the monitoring service198 and/or monitoring agent 197 measures and monitors the duration auser is logged into an application, a server, or the applicationdelivery system 190. In some embodiments, the monitoring service 198and/or monitoring agent 197 measures and monitors active and inactivesession counts for an application, server or application delivery systemsession. In yet another embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors user session latency.

In yet further embodiments, the monitoring service 198 and/or monitoringagent 197 measures and monitors measures and monitors any type and formof server metrics. In one embodiment, the monitoring service 198 and/ormonitoring agent 197 measures and monitors metrics related to systemmemory, CPU usage, and disk storage. In another embodiment, themonitoring service 198 and/or monitoring agent 197 measures and monitorsmetrics related to page faults, such as page faults per second. In otherembodiments, the monitoring service 198 and/or monitoring agent 197measures and monitors round-trip time metrics. In yet anotherembodiment, the monitoring service 198 and/or monitoring agent 197measures and monitors metrics related to application crashes, errorsand/or hangs.

In some embodiments, the monitoring service 198 and monitoring agent 198includes any of the product embodiments referred to as EdgeSightmanufactured by Citrix Systems, Inc. of Ft. Lauderdale, Fla. In anotherembodiment, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the product embodiments referred to asthe TrueView product suite manufactured by the Symphoniq Corporation ofPalo Alto, Calif. In one embodiment, the performance monitoring service198 and/or monitoring agent 198 includes any portion of the productembodiments referred to as the TeaLeaf CX product suite manufactured bythe TeaLeaf Technology Inc. of San Francisco, Calif. In otherembodiments, the performance monitoring service 198 and/or monitoringagent 198 includes any portion of the business service managementproducts, such as the BMC Performance Manager and Patrol products,manufactured by BMC Software, Inc. of Houston, Tex.

The client 102, server 106, and appliance 200 may be deployed as and/orexecuted on any type and form of computing device, such as a computer,network device or appliance capable of communicating on any type andform of network and performing the operations described herein. FIGS. 1Eand 1F depict block diagrams of a computing device 100 useful forpracticing an embodiment of the client 102, server 106 or appliance 200.As shown in FIGS. 1E and 1F, each computing device 100 includes acentral processing unit 101, and a main memory unit 122. As shown inFIG. 1E, a computing device 100 may include a visual display device 124,a keyboard 126 and/or a pointing device 127, such as a mouse. Eachcomputing device 100 may also include additional optional elements, suchas one or more input/output devices 130 a-130 b (generally referred tousing reference numeral 130), and a cache memory 140 in communicationwith the central processing unit 101.

The central processing unit 101 is any logic circuitry that responds toand processes instructions fetched from the main memory unit 122. Inmany embodiments, the central processing unit is provided by amicroprocessor unit, such as: those manufactured by Intel Corporation ofMountain View, Calif.; those manufactured by Motorola Corporation ofSchaumburg, Ill.; those manufactured by Transmeta Corporation of SantaClara, Calif.; the RS/6000 processor, those manufactured byInternational Business Machines of White Plains, N.Y.; or thosemanufactured by Advanced Micro Devices of Sunnyvale, Calif. Thecomputing device 100 may be based on any of these processors, or anyother processor capable of operating as described herein.

Main memory unit 122 may be one or more memory chips capable of storingdata and allowing any storage location to be directly accessed by themicroprocessor 101, such as Static random access memory (SRAM), BurstSRAM or SynchBurst SRAM (BSRAM), Dynamic random access memory (DRAM),Fast Page Mode DRAM (FPM DRAM), Enhanced DRAM (EDRAM), Extended DataOutput RAM (EDO RAM), Extended Data Output DRAM (EDO DRAM), BurstExtended Data Output DRAM (BEDO DRAM), Enhanced DRAM (EDRAM),synchronous DRAM (SDRAM), JEDEC SRAM, PC100 SDRAM, Double Data RateSDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), SyncLink DRAM (SLDRAM),Direct Rambus DRAM (DRDRAM), or Ferroelectric RAM (FRAM). The mainmemory 122 may be based on any of the above described memory chips, orany other available memory chips capable of operating as describedherein. In the embodiment shown in FIG. 1E, the processor 101communicates with main memory 122 via a system bus 150 (described inmore detail below). FIG. 1F depicts an embodiment of a computing device100 in which the processor communicates directly with main memory 122via a memory port 103. For example, in FIG. 1F the main memory 122 maybe DRDRAM.

FIG. 1F depicts an embodiment in which the main processor 101communicates directly with cache memory 140 via a secondary bus,sometimes referred to as a backside bus. In other embodiments, the mainprocessor 101 communicates with cache memory 140 using the system bus150. Cache memory 140 typically has a faster response time than mainmemory 122 and is typically provided by SRAM, BSRAM, or EDRAM. In theembodiment shown in FIG. 1F, the processor 101 communicates with variousI/O devices 130 via a local system bus 150. Various busses may be usedto connect the central processing unit 101 to any of the I/O devices130, including a VESA VL bus, an ISA bus, an EISA bus, a MicroChannelArchitecture (MCA) bus, a PCI bus, a PCI-X bus, a PCI-Express bus, or aNuBus. For embodiments in which the I/O device is a video display 124,the processor 101 may use an Advanced Graphics Port (AGP) to communicatewith the display 124. FIG. 1F depicts an embodiment of a computer 100 inwhich the main processor 101 communicates directly with I/O device 130 bvia HyperTransport, Rapid I/O, or InfiniBand. FIG. 1F also depicts anembodiment in which local busses and direct communication are mixed: theprocessor 101 communicates with I/O device 130 b using a localinterconnect bus while communicating with I/O device 130 a directly.

The computing device 100 may support any suitable installation device116, such as a floppy disk drive for receiving floppy disks such as3.5-inch, 5.25-inch disks or ZIP disks, a CD-ROM drive, a CD-R/RW drive,a DVD-ROM drive, tape drives of various formats, USB device, hard-driveor any other device suitable for installing software and programs suchas any client agent 120, or portion thereof. The computing device 100may further comprise a storage device 128, such as one or more hard diskdrives or redundant arrays of independent disks, for storing anoperating system and other related software, and for storing applicationsoftware programs such as any program related to the client agent 120.Optionally, any of the installation devices 116 could also be used asthe storage device 128. Additionally, the operating system and thesoftware can be run from a bootable medium, for example, a bootable CD,such as KNOPPIX®, a bootable CD for GNU/Linux that is available as aGNU/Linux distribution from knoppix.net.

Furthermore, the computing device 100 may include a network interface118 to interface to a Local Area Network (LAN), Wide Area Network (WAN)or the Internet through a variety of connections including, but notlimited to, standard telephone lines, LAN or WAN links (e.g., 802.11,T1, T3, 56 kb, X.25), broadband connections (e.g., ISDN, Frame Relay,ATM), wireless connections, or some combination of any or all of theabove. The network interface 118 may comprise a built-in networkadapter, network interface card, PCMCIA network card, card bus networkadapter, wireless network adapter, USB network adapter, modem or anyother device suitable for interfacing the computing device 100 to anytype of network capable of communication and performing the operationsdescribed herein. A wide variety of I/O devices 130 a-130 n may bepresent in the computing device 100. Input devices include keyboards,mice, trackpads, trackballs, microphones, and drawing tablets. Outputdevices include video displays, speakers, inkjet printers, laserprinters, and dye-sublimation printers. The I/O devices 130 may becontrolled by an I/O controller 123 as shown in FIG. 1E. The I/Ocontroller may control one or more I/O devices such as a keyboard 126and a pointing device 127, e.g., a mouse or optical pen. Furthermore, anI/O device may also provide storage 128 and/or an installation medium116 for the computing device 100. In still other embodiments, thecomputing device 100 may provide USB connections to receive handheld USBstorage devices such as the USB Flash Drive line of devices manufacturedby Twintech Industry, Inc. of Los Alamitos, Calif.

In some embodiments, the computing device 100 may comprise or beconnected to multiple display devices 124 a-124 n, which each may be ofthe same or different type and/or form. As such, any of the I/O devices130 a-130 n and/or the I/O controller 123 may comprise any type and/orform of suitable hardware, software, or combination of hardware andsoftware to support, enable or provide for the connection and use ofmultiple display devices 124 a-124 n by the computing device 100. Forexample, the computing device 100 may include any type and/or form ofvideo adapter, video card, driver, and/or library to interface,communicate, connect or otherwise use the display devices 124 a-124 n.In one embodiment, a video adapter may comprise multiple connectors tointerface to multiple display devices 124 a-124 n. In other embodiments,the computing device 100 may include multiple video adapters, with eachvideo adapter connected to one or more of the display devices 124 a-124n. In some embodiments, any portion of the operating system of thecomputing device 100 may be configured for using multiple displays 124a-124 n. In other embodiments, one or more of the display devices 124a-124 n may be provided by one or more other computing devices, such ascomputing devices 100 a and 100 b connected to the computing device 100,for example, via a network. These embodiments may include any type ofsoftware designed and constructed to use another computer's displaydevice as a second display device 124 a for the computing device 100.One ordinarily skilled in the art will recognize and appreciate thevarious ways and embodiments that a computing device 100 may beconfigured to have multiple display devices 124 a-124 n.

In further embodiments, an I/O device 130 may be a bridge 170 betweenthe system bus 150 and an external communication bus, such as a USB bus,an Apple Desktop Bus, an RS-232 serial connection, a SCSI bus, aFireWire bus, a FireWire 800 bus, an Ethernet bus, an AppleTalk bus, aGigabit Ethernet bus, an Asynchronous Transfer Mode bus, a HIPPI bus, aSuper HIPPI bus, a SerialPlus bus, a SCI/LAMP bus, a FibreChannel bus,or a Serial Attached small computer system interface bus.

A computing device 100 of the sort depicted in FIGS. 1E and 1F typicallyoperate under the control of operating systems, which control schedulingof tasks and access to system resources. The computing device 100 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any real-time operatingsystem, any open source operating system, any proprietary operatingsystem, any operating systems for mobile computing devices, or any otheroperating system capable of running on the computing device andperforming the operations described herein. Typical operating systemsinclude: WINDOWS 3.x, WINDOWS 95, WINDOWS 98, WINDOWS 2000, WINDOWS NT3.51, WINDOWS NT 4.0, WINDOWS CE, WINDOWS XP, WINDOWS 7, WINDOWS 8, andWINDOWS SERVER 2012, all of which are manufactured by MicrosoftCorporation of Redmond, Wash.; MacOS, manufactured by Apple Computer ofCupertino, Calif.; OS/2, manufactured by International Business Machinesof Armonk, N.Y.; and Linux, a freely-available operating systemdistributed by Caldera Corp. of Salt Lake City, Utah, or any type and/orform of a Unix operating system, among others.

In other embodiments, the computing device 100 may have differentprocessors, operating systems, and input devices consistent with thedevice. For example, in one embodiment the computer 100 is a Treo 180,270, 1060, 600 or 650 smart phone manufactured by Palm, Inc. In thisembodiment, the Treo smart phone is operated under the control of thePalmOS operating system and includes a stylus input device as well as afive-way navigator device. Moreover, the computing device 100 can be anyworkstation, desktop computer, laptop or notebook computer, server,handheld computer, mobile telephone, any other computer, or other formof computing or telecommunications device that is capable ofcommunication and that has sufficient processor power and memorycapacity to perform the operations described herein.

As shown in FIG. 1G, the computing device 100 may comprise multipleprocessors and may provide functionality for simultaneous execution ofinstructions or for simultaneous execution of one instruction on morethan one piece of data. In some embodiments, the computing device 100may comprise a parallel processor with one or more cores. In one ofthese embodiments, the computing device 100 is a shared memory paralleldevice, with multiple processors and/or multiple processor cores,accessing all available memory as a single global address space. Inanother of these embodiments, the computing device 100 is a distributedmemory parallel device with multiple processors each accessing localmemory only. In still another of these embodiments, the computing device100 has both some memory which is shared and some memory which can onlybe accessed by particular processors or subsets of processors. In stilleven another of these embodiments, the computing device 100, such as amulti-core microprocessor, combines two or more independent processorsinto a single package, often a single integrated circuit (IC). In yetanother of these embodiments, the computing device 100 includes a chiphaving a CELL BROADBAND ENGINE architecture and including a Powerprocessor element and a plurality of synergistic processing elements,the Power processor element and the plurality of synergistic processingelements linked together by an internal high speed bus, which may bereferred to as an element interconnect bus.

In some embodiments, the processors provide functionality for executionof a single instruction simultaneously on multiple pieces of data(SIMD). In other embodiments, the processors provide functionality forexecution of multiple instructions simultaneously on multiple pieces ofdata (MIMD). In still other embodiments, the processor may use anycombination of SIMD and MIMD cores in a single device.

In some embodiments, the computing device 100 may comprise a graphicsprocessing unit. In one of these embodiments, depicted in FIG. 1H, thecomputing device 100 includes at least one central processing unit 101and at least one graphics processing unit. In another of theseembodiments, the computing device 100 includes at least one parallelprocessing unit and at least one graphics processing unit. In stillanother of these embodiments, the computing device 100 includes aplurality of processing units of any type, one of the plurality ofprocessing units comprising a graphics processing unit.

In some embodiments, a first computing device 100, e.g., a server 106 a,executes an application on behalf of a user of a client computing device100, e.g., a client 102 a. In other embodiments, a computing device 100,e.g., a server 106 a, executes a virtual machine, which provides anexecution session within which applications execute on behalf of a useror a client computing devices 100, e.g., a client 102 a. In one of theseembodiments, the execution session is a hosted desktop session. Inanother of these embodiments, the computing device 100 executes aterminal services session. The terminal services session may provide ahosted desktop environment. In still another of these embodiments, theexecution session provides access to a computing environment, which maycomprise one or more of: an application, a plurality of applications, adesktop application, and a desktop session in which one or moreapplications may execute.

B. Appliance Architecture

FIG. 2A illustrates an example embodiment of the appliance 200. Thearchitecture of the appliance 200 in FIG. 2A is provided by way ofillustration only and is not intended to be limiting. As shown in FIG.2, appliance 200 comprises a hardware layer 206 and a software layerdivided into a user space 202 and a kernel space 204.

Hardware layer 206 provides the hardware elements upon which programsand services within kernel space 204 and user space 202 are executed.Hardware layer 206 also provides the structures and elements which allowprograms and services within kernel space 204 and user space 202 tocommunicate data both internally and externally with respect toappliance 200. As shown in FIG. 2, the hardware layer 206 includes aprocessing unit 262 for executing software programs and services, amemory 264 for storing software and data, network ports 266 fortransmitting and receiving data over a network, and an encryptionprocessor 260 for performing functions related to Secure Sockets Layerprocessing of data transmitted and received over the network. In someembodiments, the central processing unit 262 may perform the functionsof the encryption processor 260 in a single processor. Additionally, thehardware layer 206 may comprise multiple processors for each of theprocessing unit 262 and the encryption processor 260. The processor 262may include any of the processors 101 described above in connection withFIGS. 1E and 1F. For example, in one embodiment, the appliance 200comprises a first processor 262 and a second processor 262′. In otherembodiments, the processor 262 or 262′ comprises a multi-core processor.

Although the hardware layer 206 of appliance 200 is generallyillustrated with an encryption processor 260, processor 260 may be aprocessor for performing functions related to any encryption protocol,such as the Secure Socket Layer (SSL) or Transport Layer Security (TLS)protocol. In some embodiments, the processor 260 may be a generalpurpose processor (GPP), and in further embodiments, may have executableinstructions for performing processing of any security related protocol.

Although the hardware layer 206 of appliance 200 is illustrated withcertain elements in FIG. 2, the hardware portions or components ofappliance 200 may comprise any type and form of elements, hardware orsoftware, of a computing device, such as the computing device 100illustrated and discussed herein in conjunction with FIGS. 1E and 1F. Insome embodiments, the appliance 200 may comprise a server, gateway,router, switch, bridge or other type of computing or network device, andhave any hardware and/or software elements associated therewith.

The operating system of appliance 200 allocates, manages, or otherwisesegregates the available system memory into kernel space 204 and userspace 204. In example software architecture 200, the operating systemmay be any type and/or form of Unix operating system although thepresent solution is not so limited. As such, the appliance 200 can berunning any operating system such as any of the versions of theMicrosoft® Windows operating systems, the different releases of the Unixand Linux operating systems, any version of the Mac OS® for Macintoshcomputers, any embedded operating system, any network operating system,any real-time operating system, any open source operating system, anyproprietary operating system, any operating systems for mobile computingdevices or network devices, or any other operating system capable ofrunning on the appliance 200 and performing the operations describedherein.

The kernel space 204 is reserved for running the kernel 230, includingany device drivers, kernel extensions or other kernel related software.As known to those skilled in the art, the kernel 230 is the core of theoperating system, and provides access, control, and management ofresources and hardware-related elements of the application 104. Inaccordance with an embodiment of the appliance 200, the kernel space 204also includes a number of network services or processes working inconjunction with a cache manager 232, sometimes also referred to as theintegrated cache, the benefits of which are described in detail furtherherein. Additionally, the embodiment of the kernel 230 will depend onthe embodiment of the operating system installed, configured, orotherwise used by the device 200.

In one embodiment, the device 200 comprises one network stack 267, suchas a TCP/IP based stack, for communicating with the client 102 and/orthe server 106. In one embodiment, the network stack 267 is used tocommunicate with a first network, such as network 104, and a secondnetwork 104′. In some embodiments, the device 200 terminates a firsttransport layer connection, such as a TCP connection of a client 102,and establishes a second transport layer connection to a server 106 foruse by the client 102, e.g., the second transport layer connection isterminated at the appliance 200 and the server 106. The first and secondtransport layer connections may be established via a single networkstack 267. In other embodiments, the device 200 may comprise multiplenetwork stacks, for example a first stack 267 and a second stack 267,and the first transport layer connection may be established orterminated at one network stack 267, and the second transport layerconnection on the second network stack 267. For example, one networkstack may be for receiving and transmitting network packet on a firstnetwork, and another network stack for receiving and transmittingnetwork packets on a second network. In one embodiment, the networkstack 267 comprises a buffer 243 for queuing one or more network packetsfor transmission by the appliance 200.

As shown in FIG. 2A, the kernel space 204 includes the cache manager232, a high-speed layer 2-7 integrated packet engine 240, an encryptionengine 234, a policy engine 236 and multi-protocol compression logic238. Running these components or processes 232, 240, 234, 236 and 238 inkernel space 204 or kernel mode instead of the user space 202 improvesthe performance of each of these components, alone and in combination.Kernel operation means that these components or processes 232, 240, 234,236 and 238 run in the core address space of the operating system of thedevice 200. For example, running the encryption engine 234 in kernelmode improves encryption performance by moving encryption and decryptionoperations to the kernel, thereby reducing the number of transitionsbetween the memory space or a kernel thread in kernel mode and thememory space or a thread in user mode. For example, data obtained inkernel mode may not need to be passed or copied to a process or threadrunning in user mode, such as from a kernel level data structure to auser level data structure. In another aspect, the number of contextswitches between kernel mode and user mode are also reduced.Additionally, synchronization of and communications between any of thecomponents or processes 232, 240, 235, 236 and 238 can be performed moreefficiently in the kernel space 204.

In some embodiments, any portion of the components 232, 240, 234, 236and 238 may run or operate in the kernel space 204, while other portionsof these components 232, 240, 234, 236 and 238 may run or operate inuser space 202. In one embodiment, the appliance 200 uses a kernel-leveldata structure providing access to any portion of one or more networkpackets, for example, a network packet comprising a request from aclient 102 or a response from a server 106. In some embodiments, thekernel-level data structure may be obtained by the packet engine 240 viaa transport layer driver interface or filter to the network stack 267.The kernel-level data structure may comprise any interface and/or dataaccessible via the kernel space 204 related to the network stack 267,network traffic or packets received or transmitted by the network stack267. In other embodiments, the kernel-level data structure may be usedby any of the components or processes 232, 240, 234, 236 and 238 toperform the desired operation of the component or process. In oneembodiment, a component 232, 240, 234, 236 and 238 is running in kernelmode 204 when using the kernel-level data structure, while in anotherembodiment, the component 232, 240, 234, 236 and 238 is running in usermode when using the kernel-level data structure. In some embodiments,the kernel-level data structure may be copied or passed to a secondkernel-level data structure, or any desired user-level data structure.

The cache manager 232 may comprise software, hardware or any combinationof software and hardware to provide cache access, control and managementof any type and form of content, such as objects or dynamicallygenerated objects served by the originating servers 106. The data,objects or content processed and stored by the cache manager 232 maycomprise data in any format, such as a markup language, or communicatedvia any protocol. In some embodiments, the cache manager 232 duplicatesoriginal data stored elsewhere or data previously computed, generated ortransmitted, in which the original data may require longer access timeto fetch, compute or otherwise obtain relative to reading a cache memoryelement. Once the data is stored in the cache memory element, future usecan be made by accessing the cached copy rather than refetching orrecomputing the original data, thereby reducing the access time. In someembodiments, the cache memory element may comprise a data object inmemory 264 of device 200. In other embodiments, the cache memory elementmay comprise memory having a faster access time than memory 264. Inanother embodiment, the cache memory element may comprise any type andform of storage element of the device 200, such as a portion of a harddisk. In some embodiments, the processing unit 262 may provide cachememory for use by the cache manager 232. In yet further embodiments, thecache manager 232 may use any portion and combination of memory,storage, or the processing unit for caching data, objects, and othercontent.

Furthermore, the cache manager 232 includes any logic, functions, rules,or operations to perform any embodiments of the techniques of theappliance 200 described herein. For example, the cache manager 232includes logic or functionality to invalidate objects based on theexpiration of an invalidation time period or upon receipt of aninvalidation command from a client 102 or server 106. In someembodiments, the cache manager 232 may operate as a program, service,process or task executing in the kernel space 204, and in otherembodiments, in the user space 202. In one embodiment, a first portionof the cache manager 232 executes in the user space 202 while a secondportion executes in the kernel space 204. In some embodiments, the cachemanager 232 can comprise any type of general purpose processor (GPP), orany other type of integrated circuit, such as a Field Programmable GateArray (FPGA), Programmable Logic Device (PLD), or Application SpecificIntegrated Circuit (ASIC).

The policy engine 236 may include, for example, an intelligentstatistical engine or other programmable application(s). In oneembodiment, the policy engine 236 provides a configuration mechanism toallow a user to identify, specify, define or configure a caching policy.Policy engine 236, in some embodiments, also has access to memory tosupport data structures such as lookup tables or hash tables to enableuser-selected caching policy decisions. In other embodiments, the policyengine 236 may comprise any logic, rules, functions or operations todetermine and provide access, control and management of objects, data orcontent being cached by the appliance 200 in addition to access, controland management of security, network traffic, network access, compressionor any other function or operation performed by the appliance 200.Further examples of specific caching policies are further describedherein.

The encryption engine 234 comprises any logic, business rules, functionsor operations for handling the processing of any security relatedprotocol, such as SSL or TLS, or any function related thereto. Forexample, the encryption engine 234 encrypts and decrypts networkpackets, or any portion thereof, communicated via the appliance 200. Theencryption engine 234 may also setup or establish SSL or TLS connectionson behalf of the client 102 a-102 n, server 106 a-106 n, or appliance200. As such, the encryption engine 234 provides offloading andacceleration of SSL processing. In one embodiment, the encryption engine234 uses a tunneling protocol to provide a virtual private networkbetween a client 102 a-102 n and a server 106 a-106 n. In someembodiments, the encryption engine 234 is in communication with theEncryption processor 260. In other embodiments, the encryption engine234 comprises executable instructions running on the Encryptionprocessor 260.

The multi-protocol compression engine 238 comprises any logic, businessrules, function or operations for compressing one or more protocols of anetwork packet, such as any of the protocols used by the network stack267 of the device 200. In one embodiment, multi-protocol compressionengine 238 compresses bi-directionally between clients 102 a-102 n andservers 106 a-106 n any TCP/IP based protocol, including MessagingApplication Programming Interface (MAPI) (email), File Transfer Protocol(FTP), HyperText Transfer Protocol (HTTP), Common Internet File System(CIFS) protocol (file transfer), Independent Computing Architecture(ICA) protocol, Remote Desktop Protocol (RDP), Wireless ApplicationProtocol (WAP), Mobile IP protocol, and Voice Over IP (VoIP) protocol.In other embodiments, multi-protocol compression engine 238 providescompression of Hypertext Markup Language (HTML) based protocols and insome embodiments, provides compression of any markup languages, such asthe Extensible Markup Language (XML). In one embodiment, themulti-protocol compression engine 238 provides compression of anyhigh-performance protocol, such as any protocol designed for applianceto appliance communications. In another embodiment, the multi-protocolcompression engine 238 compresses any payload of or any communicationusing a modified transport control protocol, such as Transaction TCP(T/TCP), TCP with selection acknowledgements (TCP-SACK), TCP with largewindows (TCP-LW), a congestion prediction protocol such as the TCP-Vegasprotocol, and a TCP spoofing protocol.

As such, the multi-protocol compression engine 238 acceleratesperformance for users accessing applications via desktop clients, e.g.,Microsoft Outlook and non-Web thin clients, such as any client launchedby popular enterprise applications like Oracle, SAP and Siebel, and evenmobile clients, such as the Pocket PC or Android. In some embodiments,the multi-protocol compression engine 238 by executing in the kernelmode 204 and integrating with packet processing engine 240 accessing thenetwork stack 267 is able to compress any of the protocols carried bythe TCP/IP protocol, such as any application layer protocol.

High speed layer 2-7 integrated packet engine 240, also generallyreferred to as a packet processing engine or packet engine, isresponsible for managing the kernel-level processing of packets receivedand transmitted by appliance 200 via network ports 266. The high speedlayer 2-7 integrated packet engine 240 may comprise a buffer for queuingone or more network packets during processing, such as for receipt of anetwork packet or transmission of a network packet. Additionally, thehigh speed layer 2-7 integrated packet engine 240 is in communicationwith one or more network stacks 267 to send and receive network packetsvia network ports 266. The high speed layer 2-7 integrated packet engine240 works in conjunction with encryption engine 234, cache manager 232,policy engine 236 and multi-protocol compression logic 238. Inparticular, encryption engine 234 is configured to perform SSLprocessing of packets, policy engine 236 is configured to performfunctions related to traffic management such as request-level contentswitching and request-level cache redirection, and multi-protocolcompression logic 238 is configured to perform functions related tocompression and decompression of data.

The high speed layer 2-7 integrated packet engine 240 includes a packetprocessing timer 242. In one embodiment, the packet processing timer 242provides one or more time intervals to trigger the processing ofincoming, i.e., received, or outgoing, i.e., transmitted, networkpackets. In some embodiments, the high speed layer 2-7 integrated packetengine 240 processes network packets responsive to the timer 242. Thepacket processing timer 242 provides any type and form of signal to thepacket engine 240 to notify, trigger, or communicate a time relatedevent, interval or occurrence. In many embodiments, the packetprocessing timer 242 operates in the order of milliseconds, such as forexample 100 ms, 50 ms or 25 ms. For example, in some embodiments, thepacket processing timer 242 provides time intervals or otherwise causesa network packet to be processed by the high speed layer 2-7 integratedpacket engine 240 at a 10 ms time interval, while in other embodiments,at a 5 ms time interval, and still yet in further embodiments, as shortas a 3, 2, or 1 ms time interval. The high speed layer 2-7 integratedpacket engine 240 may be interfaced, integrated or in communication withthe encryption engine 234, cache manager 232, policy engine 236 andmulti-protocol compression engine 238 during operation. As such, any ofthe logic, functions, or operations of the encryption engine 234, cachemanager 232, policy engine 236 and multi-protocol compression logic 238may be performed responsive to the packet processing timer 242 and/orthe packet engine 240. Therefore, any of the logic, functions, oroperations of the encryption engine 234, cache manager 232, policyengine 236 and multi-protocol compression logic 238 may be performed atthe granularity of time intervals provided via the packet processingtimer 242, for example, at a time interval of less than or equal to 10ms. For example, in one embodiment, the cache manager 232 may performinvalidation of any cached objects responsive to the high speed layer2-7 integrated packet engine 240 and/or the packet processing timer 242.In another embodiment, the expiry or invalidation time of a cachedobject can be set to the same order of granularity as the time intervalof the packet processing timer 242, such as at every 10 ms.

In contrast to kernel space 204, user space 202 is the memory area orportion of the operating system used by user mode applications orprograms otherwise running in user mode. A user mode application may notaccess kernel space 204 directly and uses service calls in order toaccess kernel services. As shown in FIG. 2A, user space 202 of appliance200 includes a graphical user interface (GUI) 210, a command lineinterface (CLI) 212, shell services 214, health monitoring program 216,and daemon services 218. GUI 210 and CLI 212 provide a means by which asystem administrator or other user can interact with and control theoperation of appliance 200, such as via the operating system of theappliance 200. The GUI 210 or CLI 212 can comprise code running in userspace 202 or kernel space 204. The GUI 210 may be any type and form ofgraphical user interface and may be presented via text, graphical orotherwise, by any type of program or application, such as a browser. TheCLI 212 may be any type and form of command line or text-basedinterface, such as a command line provided by the operating system. Forexample, the CLI 212 may comprise a shell, which is a tool to enableusers to interact with the operating system. In some embodiments, theCLI 212 may be provided via a bash, csh, tcsh, or ksh type shell. Theshell services 214 comprises the programs, services, tasks, processes orexecutable instructions to support interaction with the appliance 200 oroperating system by a user via the GUI 210 and/or CLI 212.

Health monitoring program 216 is used to monitor, check, report andensure that network systems are functioning properly and that users arereceiving requested content over a network. Health monitoring program216 comprises one or more programs, services, tasks, processes orexecutable instructions to provide logic, rules, functions or operationsfor monitoring any activity of the appliance 200. In some embodiments,the health monitoring program 216 intercepts and inspects any networktraffic passed via the appliance 200. In other embodiments, the healthmonitoring program 216 interfaces by any suitable means and/ormechanisms with one or more of the following: the encryption engine 234,cache manager 232, policy engine 236, multi-protocol compression logic238, packet engine 240, daemon services 218, and shell services 214. Assuch, the health monitoring program 216 may call any applicationprogramming interface (API) to determine a state, status, or health ofany portion of the appliance 200. For example, the health monitoringprogram 216 may ping or send a status inquiry on a periodic basis tocheck if a program, process, service or task is active and currentlyrunning. In another example, the health monitoring program 216 may checkany status, error or history logs provided by any program, process,service or task to determine any condition, status or error with anyportion of the appliance 200.

Daemon services 218 are programs that run continuously or in thebackground and handle periodic service requests received by appliance200. In some embodiments, a daemon service may forward the requests toother programs or processes, such as another daemon service 218 asappropriate. As known to those skilled in the art, a daemon service 218may run unattended to perform continuous or periodic system widefunctions, such as network control, or to perform any desired task. Insome embodiments, one or more daemon services 218 run in the user space202; in some embodiments, one or more daemon services 218 run in thekernel space.

Referring now to FIG. 2B, another embodiment of the appliance 200 isdepicted. In brief overview, the appliance 200 provides one or more ofthe following services, functionality or operations: SSL VPNconnectivity 280, switching/load balancing 284, Domain Name Serviceresolution 286, acceleration 288 and an application firewall 290 forcommunications between one or more clients 102 and one or more servers106. Each of the servers 106 may provide one or more network relatedservices 270 a-270 n (referred to as services 270). For example, aserver 106 may provide an http service 270. The appliance 200 comprisesone or more virtual servers or virtual internet protocol servers,referred to as a vServer, VIP server, or just VIP 275 a-275 n (alsoreferred herein as vServer 275). The vServer 275 receives, intercepts orotherwise processes communications between a client 102 and a server 106in accordance with the configuration and operations of the appliance200.

The vServer 275 may comprise software, hardware or any combination ofsoftware and hardware. The vServer 275 may comprise any type and form ofprogram, service, task, process or executable instructions operating inuser mode 202, kernel mode 204 or any combination thereof in theappliance 200. The vServer 275 includes any logic, functions, rules, oroperations to perform any embodiments of the techniques describedherein, such as SSL VPN 280, switching/load balancing 284, Domain NameService resolution 286, acceleration 288 and an application firewall290. In some embodiments, the vServer 275 establishes a connection to aservice 270 of a server 106. The service 270 may comprise any program,application, process, task or set of executable instructions capable ofconnecting to and communicating with the appliance 200, client 102 orvServer 275. For example, the service 270 may comprise a web server,http server, ftp, email or database server. In some embodiments, theservice 270 is a daemon process or network driver for listening,receiving and/or sending communications for an application, such asemail, database or an enterprise application. In some embodiments, theservice 270 may communicate on a specific IP address, or IP address andport.

In some embodiments, the vServer 275 applies one or more policies of thepolicy engine 236 to network communications between the client 102 andserver 106. In one embodiment, the policies are associated with avServer 275. In another embodiment, the policies are based on a user, ora group of users. In yet another embodiment, a policy is global andapplies to one or more vServers 275 a-275 n, and any user or group ofusers communicating via the appliance 200. In some embodiments, thepolicies of the policy engine 236 have conditions upon which the policyis applied based on any content of the communication, such as internetprotocol address, port, protocol type, header or fields in a packet, orthe context of the communication, such as user, group of the user,vServer 275, transport layer connection, and/or identification orattributes of the client 102 or server 106.

In other embodiments, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to access the computingenvironment 15, application, and/or data file from a server 106. Inanother embodiment, the appliance 200 communicates or interfaces withthe policy engine 236 to determine authentication and/or authorizationof a remote user or a remote client 102 to have the application deliverysystem 190 deliver one or more of the computing environment 15,application, and/or data file. In yet another embodiment, the appliance200 establishes a VPN or SSL VPN connection based on the policy engine's236 authentication and/or authorization of a remote user or a remoteclient 102. In one embodiment, the appliance 200 controls the flow ofnetwork traffic and communication sessions based on policies of thepolicy engine 236. For example, the appliance 200 may control the accessto a computing environment 15, application or data file based on thepolicy engine 236.

In some embodiments, the vServer 275 establishes a transport layerconnection, such as a TCP or UDP connection with a client 102 via theclient agent 120. In one embodiment, the vServer 275 listens for andreceives communications from the client 102. In other embodiments, thevServer 275 establishes a transport layer connection, such as a TCP orUDP connection with a client server 106. In one embodiment, the vServer275 establishes the transport layer connection to an internet protocoladdress and port of a server 270 running on the server 106. In anotherembodiment, the vServer 275 associates a first transport layerconnection to a client 102 with a second transport layer connection tothe server 106. In some embodiments, a vServer 275 establishes a pool oftransport layer connections to a server 106 and multiplexes clientrequests via the pooled transport layer connections.

In some embodiments, the appliance 200 provides a SSL VPN connection 280between a client 102 and a server 106. For example, a client 102 on afirst network 102 requests to establish a connection to a server 106 ona second network 104′. In some embodiments, the second network 104′ isnot routable from the first network 104. In other embodiments, theclient 102 is on a public network 104 and the server 106 is on a privatenetwork 104′, such as a corporate network. In one embodiment, the clientagent 120 intercepts communications of the client 102 on the firstnetwork 104, encrypts the communications, and transmits thecommunications via a first transport layer connection to the appliance200. The appliance 200 associates the first transport layer connectionon the first network 104 to a second transport layer connection to theserver 106 on the second network 104. The appliance 200 receives theintercepted communication from the client agent 102, decrypts thecommunications, and transmits the communication to the server 106 on thesecond network 104 via the second transport layer connection. The secondtransport layer connection may be a pooled transport layer connection.As such, the appliance 200 provides an end-to-end secure transport layerconnection for the client 102 between the two networks 104, 104′.

In one embodiment, the appliance 200 hosts an intranet internet protocolor IntranetIP 282 address of the client 102 on the virtual privatenetwork 104. The client 102 has a local network identifier, such as aninternet protocol (IP) address and/or host name on the first network104. When connected to the second network 104′ via the appliance 200,the appliance 200 establishes, assigns or otherwise provides anIntranetIP address 282, which is a network identifier, such as IPaddress and/or host name, for the client 102 on the second network 104′.The appliance 200 listens for and receives on the second or privatenetwork 104′ for any communications directed towards the client 102using the client's established IntranetIP 282. In one embodiment, theappliance 200 acts as or on behalf of the client 102 on the secondprivate network 104. For example, in another embodiment, a vServer 275listens for and responds to communications to the IntranetIP 282 of theclient 102. In some embodiments, if a computing device 100 on the secondnetwork 104′ transmits a request, the appliance 200 processes therequest as if it were the client 102. For example, the appliance 200 mayrespond to a ping to the client's IntranetIP 282. In another example,the appliance may establish a connection, such as a TCP or UDPconnection, with computing device 100 on the second network 104requesting a connection with the client's IntranetIP 282.

In some embodiments, the appliance 200 provides one or more of thefollowing acceleration techniques 288 to communications between theclient 102 and server 106: 1) compression; 2) decompression; 3)Transmission Control Protocol pooling; 4) Transmission Control Protocolmultiplexing; 5) Transmission Control Protocol buffering; and 6)caching. In one embodiment, the appliance 200 relieves servers 106 ofmuch of the processing load caused by repeatedly opening and closingtransport layers connections to clients 102 by opening one or moretransport layer connections with each server 106 and maintaining theseconnections to allow repeated data accesses by clients via the Internet.This technique is referred to herein as “connection pooling”.

In some embodiments, in order to seamlessly splice communications from aclient 102 to a server 106 via a pooled transport layer connection, theappliance 200 translates or multiplexes communications by modifyingsequence number and acknowledgment numbers at the transport layerprotocol level. This is referred to as “connection multiplexing”. Insome embodiments, no application layer protocol interaction is required.For example, in the case of an in-bound packet (that is, a packetreceived from a client 102), the source network address of the packet ischanged to that of an output port of appliance 200, and the destinationnetwork address is changed to that of the intended server. In the caseof an outbound packet (that is, one received from a server 106), thesource network address is changed from that of the server 106 to that ofan output port of appliance 200 and the destination address is changedfrom that of appliance 200 to that of the destination client 102. Thesequence numbers and acknowledgment numbers of the packet are alsotranslated to sequence numbers and acknowledgement numbers expected bythe client 102 on the appliance's 200 transport layer connection to theclient 102. In some embodiments, the packet checksum of the transportlayer protocol is recalculated to account for these translations.

In another embodiment, the appliance 200 provides switching orload-balancing functionality 284 for communications between the client102 and server 106. In some embodiments, the appliance 200 distributestraffic and directs client requests to a server 106 based on layer 4 orapplication-layer request data. In one embodiment, although the networklayer or layer 2 of the network packet identifies a destination server106, the appliance 200 determines the server 106 to distribute thenetwork packet by application information and data carried as payload ofthe transport layer packet. In one embodiment, the health monitoringprograms 216 of the appliance 200 monitor the health of servers todetermine the server 106 for which to distribute a client's request. Insome embodiments, if the appliance 200 detects a server 106 is notavailable or has a load over a predetermined threshold, the appliance200 can direct or distribute client requests to another server 106.

In some embodiments, the appliance 200 acts as a Domain Name Service(DNS) resolver or otherwise provides resolution of a DNS request fromclients 102. In some embodiments, the appliance intercepts a DNS requesttransmitted by the client 102. In one embodiment, the appliance 200responds to a client's DNS request with an IP address of or hosted bythe appliance 200. In this embodiment, the client 102 transmits networkcommunication for the domain name to the appliance 200. In anotherembodiment, the appliance 200 responds to a client's DNS request with anIP address of or hosted by a second appliance 200′. In some embodiments,the appliance 200 responds to a client's DNS request with an IP addressof a server 106 determined by the appliance 200.

In yet another embodiment, the appliance 200 provides applicationfirewall functionality 290 for communications between the client 102 andserver 106. In one embodiment, the policy engine 236 provides rules fordetecting and blocking illegitimate requests. In some embodiments, theapplication firewall 290 protects against denial of service (DoS)attacks. In other embodiments, the appliance inspects the content ofintercepted requests to identify and block application-based attacks. Insome embodiments, the rules/policy engine 236 comprises one or moreapplication firewall or security control policies for providingprotections against various classes and types of web or Internet basedvulnerabilities, such as one or more of the following: 1) bufferoverflow, 2) CGI-BIN parameter manipulation, 3) form/hidden fieldmanipulation, 4) forceful browsing, 5) cookie or session poisoning, 6)broken access control list (ACLs) or weak passwords, 7) cross-sitescripting (XSS), 8) command injection, 9) SQL injection, 10) errortriggering sensitive information leak, 11) insecure use of cryptography,12) server misconfiguration, 13) back doors and debug options, 14)website defacement, 15) platform or operating systems vulnerabilities,and 16) zero-day exploits. In an embodiment, the application firewall290 provides HTML form field protection in the form of inspecting oranalyzing the network communication for one or more of the following: 1)required fields are returned, 2) no added field allowed, 3) read-onlyand hidden field enforcement, 4) drop-down list and radio button fieldconformance, and 5) form-field max-length enforcement. In someembodiments, the application firewall 290 ensures cookies are notmodified. In other embodiments, the application firewall 290 protectsagainst forceful browsing by enforcing legal URLs.

In still yet other embodiments, the application firewall 290 protectsany confidential information contained in the network communication. Theapplication firewall 290 may inspect or analyze any networkcommunication in accordance with the rules or polices of the engine 236to identify any confidential information in any field of the networkpacket. In some embodiments, the application firewall 290 identifies inthe network communication one or more occurrences of a credit cardnumber, password, social security number, name, patient code, contactinformation, and age. The encoded portion of the network communicationmay comprise these occurrences or the confidential information. Based onthese occurrences, in one embodiment, the application firewall 290 maytake a policy action on the network communication, such as preventtransmission of the network communication. In another embodiment, theapplication firewall 290 may rewrite, remove or otherwise mask suchidentified occurrence or confidential information.

Still referring to FIG. 2B, the appliance 200 may include a performancemonitoring agent 197 as discussed above in conjunction with FIG. 1D. Inone embodiment, the appliance 200 receives the monitoring agent 197 fromthe monitoring service 198 or monitoring server 106 as depicted in FIG.1D. In some embodiments, the appliance 200 stores the monitoring agent197 in storage, such as disk, for delivery to any client or server incommunication with the appliance 200. For example, in one embodiment,the appliance 200 transmits the monitoring agent 197 to a client uponreceiving a request to establish a transport layer connection. In otherembodiments, the appliance 200 transmits the monitoring agent 197 uponestablishing the transport layer connection with the client 102. Inanother embodiment, the appliance 200 transmits the monitoring agent 197to the client upon intercepting or detecting a request for a web page.In yet another embodiment, the appliance 200 transmits the monitoringagent 197 to a client or a server in response to a request from themonitoring server 198. In one embodiment, the appliance 200 transmitsthe monitoring agent 197 to a second appliance 200′ or appliance 205.

In other embodiments, the appliance 200 executes the monitoring agent197. In one embodiment, the monitoring agent 197 measures and monitorsthe performance of any application, program, process, service, task orthread executing on the appliance 200. For example, the monitoring agent197 may monitor and measure performance and operation of vServers275A-275N. In another embodiment, the monitoring agent 197 measures andmonitors the performance of any transport layer connections of theappliance 200. In some embodiments, the monitoring agent 197 measuresand monitors the performance of any user sessions traversing theappliance 200. In one embodiment, the monitoring agent 197 measures andmonitors the performance of any virtual private network connectionsand/or sessions traversing the appliance 200, such an SSL VPN session.In still further embodiments, the monitoring agent 197 measures andmonitors the memory, CPU and disk usage and performance of the appliance200. In yet another embodiment, the monitoring agent 197 measures andmonitors the performance of any acceleration technique 288 performed bythe appliance 200, such as SSL offloading, connection pooling andmultiplexing, caching, and compression. In some embodiments, themonitoring agent 197 measures and monitors the performance of any loadbalancing and/or content switching 284 performed by the appliance 200.In other embodiments, the monitoring agent 197 measures and monitors theperformance of application firewall 290 protection and processingperformed by the appliance 200.

C. Client Agent

Referring now to FIG. 3, an embodiment of a client agent 120 isdepicted. The client 102 includes a client agent 120 for establishingand exchanging communications with the appliance 200 and/or server 106via a network 104. In brief overview, the client 102 operates oncomputing device 100 having an operating system with a kernel mode 302and a user mode 303, and a network stack 310 with one or more layers 310a-310 b. The client 102 may have installed and/or execute one or moreapplications. In some embodiments, one or more applications maycommunicate via the network stack 310 to a network 104. One of theapplications, such as a web browser, may also include a first program322. For example, the first program 322 may be used in some embodimentsto install and/or execute the client agent 120, or any portion thereofThe client agent 120 includes an interception mechanism, or interceptor350, for intercepting network communications from the network stack 310from the one or more applications.

The network stack 310 of the client 102 may comprise any type and formof software, or hardware, or any combinations thereof, for providingconnectivity to and communications with a network. In one embodiment,the network stack 310 comprises a software implementation for a networkprotocol suite. The network stack 310 may comprise one or more networklayers, such as any networks layers of the Open Systems Interconnection(OSI) communications model as those skilled in the art recognize andappreciate. As such, the network stack 310 may comprise any type andform of protocols for any of the following layers of the OSI model: 1)physical link layer, 2) data link layer, 3) network layer, 4) transportlayer, 5) session layer, 6) presentation layer, and 7) applicationlayer. In one embodiment, the network stack 310 may comprise a transportcontrol protocol (TCP) over the network layer protocol of the internetprotocol (IP), generally referred to as TCP/IP. In some embodiments, theTCP/IP protocol may be carried over the Ethernet protocol, which maycomprise any of the family of IEEE wide-area-network (WAN) orlocal-area-network (LAN) protocols, such as those protocols covered bythe IEEE 802.3. In some embodiments, the network stack 310 comprises anytype and form of a wireless protocol, such as IEEE 802.11 and/or mobileinternet protocol.

In view of a TCP/IP based network, any TCP/IP based protocol may beused, including Messaging Application Programming Interface (MAPI)(email), File Transfer Protocol (FTP), HyperText Transfer Protocol(HTTP), Common Internet File System (CIFS) protocol (file transfer),Independent Computing Architecture (ICA) protocol, Remote DesktopProtocol (RDP), Wireless Application Protocol (WAP), Mobile IP protocol,and Voice Over IP (VoIP) protocol. In another embodiment, the networkstack 310 comprises any type and form of transport control protocol,such as a modified transport control protocol, for example a TransactionTCP (T/TCP), TCP with selection acknowledgements (TCP-SAK), TCP withlarge windows (TCP-LW), a congestion prediction protocol such as theTCP-Vegas protocol, and a TCP spoofing protocol. In other embodiments,any type and form of user datagram protocol (UDP), such as UDP over IP,may be used by the network stack 310, such as for voice communicationsor real-time data communications.

Furthermore, the network stack 310 may include one or more networkdrivers supporting the one or more layers, such as a TCP driver or anetwork layer driver. The network drivers may be included as part of theoperating system of the computing device 100 or as part of any networkinterface cards or other network access components of the computingdevice 100. In some embodiments, any of the network drivers of thenetwork stack 310 may be customized, modified or adapted to provide acustom or modified portion of the network stack 310 in support of any ofthe techniques described herein. In other embodiments, the accelerationprogram 302 is designed and constructed to operate with or work inconjunction with the network stack 310 installed or otherwise providedby the operating system of the client 102.

The network stack 310 comprises any type and form of interfaces forreceiving, obtaining, providing or otherwise accessing any informationand data related to network communications of the client 102. In oneembodiment, an interface to the network stack 310 comprises anapplication programming interface (API). The interface may also compriseany function call, hooking or filtering mechanism, event or call backmechanism, or any type of interfacing technique. The network stack 310via the interface may receive or provide any type and form of datastructure, such as an object, related to functionality or operation ofthe network stack 310. For example, the data structure may compriseinformation and data related to a network packet or one or more networkpackets. In some embodiments, the data structure comprises a portion ofthe network packet processed at a protocol layer of the network stack310, such as a network packet of the transport layer. In someembodiments, the data structure 325 comprises a kernel-level datastructure, while in other embodiments, the data structure 325 comprisesa user-mode data structure. A kernel-level data structure may comprise adata structure obtained or related to a portion of the network stack 310operating in kernel-mode 302, or a network driver or other softwarerunning in kernel-mode 302, or any data structure obtained or receivedby a service, process, task, thread or other executable instructionsrunning or operating in kernel-mode of the operating system.

Additionally, some portions of the network stack 310 may execute oroperate in kernel-mode 302, for example, the data link or network layer,while other portions execute or operate in user-mode 303, such as anapplication layer of the network stack 310. For example, a first portion310 a of the network stack may provide user-mode access to the networkstack 310 to an application while a second portion 310 a of the networkstack 310 provides access to a network. In some embodiments, a firstportion 310 a of the network stack may comprise one or more upper layersof the network stack 310, such as any of layers 5-7. In otherembodiments, a second portion 310 b of the network stack 310 comprisesone or more lower layers, such as any of layers 1-4. Each of the firstportion 310 a and second portion 310 b of the network stack 310 maycomprise any portion of the network stack 310, at any one or morenetwork layers, in user-mode 303, kernel-mode, 302, or combinationsthereof, or at any portion of a network layer or interface point to anetwork layer or any portion of or interface point to the user-mode 303and kernel-mode 302.

The interceptor 350 may comprise software, hardware, or any combinationof software and hardware. In one embodiment, the interceptor 350intercepts a network communication at any point in the network stack310, and redirects or transmits the network communication to adestination desired, managed or controlled by the interceptor 350 orclient agent 120. For example, the interceptor 350 may intercept anetwork communication of a network stack 310 of a first network andtransmit the network communication to the appliance 200 for transmissionon a second network 104. In some embodiments, the interceptor 350comprises any type interceptor 350 comprises a driver, such as a networkdriver constructed and designed to interface and work with the networkstack 310. In some embodiments, the client agent 120 and/or interceptor350 operates at one or more layers of the network stack 310, such as atthe transport layer. In one embodiment, the interceptor 350 comprises afilter driver, hooking mechanism, or any form and type of suitablenetwork driver interface that interfaces to the transport layer of thenetwork stack, such as via the transport driver interface (TDI). In someembodiments, the interceptor 350 interfaces to a first protocol layer,such as the transport layer and another protocol layer, such as anylayer above the transport protocol layer, for example, an applicationprotocol layer. In one embodiment, the interceptor 350 may comprise adriver complying with the Network Driver Interface Specification (NDIS),or a NDIS driver. In another embodiment, the interceptor 350 maycomprise a mini-filter or a mini-port driver. In one embodiment, theinterceptor 350, or portion thereof, operates in kernel-mode 302. Inanother embodiment, the interceptor 350, or portion thereof, operates inuser-mode 303. In some embodiments, a portion of the interceptor 350operates in kernel-mode 302 while another portion of the interceptor 350operates in user-mode 303. In other embodiments, the client agent 120operates in user-mode 303 but interfaces via the interceptor 350 to akernel-mode driver, process, service, task or portion of the operatingsystem, such as to obtain a kernel-level data structure 225. In furtherembodiments, the interceptor 350 is a user-mode application or program,such as application.

In one embodiment, the interceptor 350 intercepts any transport layerconnection requests. In these embodiments, the interceptor 350 executetransport layer application programming interface (API) calls to set thedestination information, such as destination IP address and/or port to adesired location for the location. In this manner, the interceptor 350intercepts and redirects the transport layer connection to a IP addressand port controlled or managed by the interceptor 350 or client agent120. In one embodiment, the interceptor 350 sets the destinationinformation for the connection to a local IP address and port of theclient 102 on which the client agent 120 is listening. For example, theclient agent 120 may comprise a proxy service listening on a local IPaddress and port for redirected transport layer communications. In someembodiments, the client agent 120 then communicates the redirectedtransport layer communication to the appliance 200.

In some embodiments, the interceptor 350 intercepts a Domain NameService (DNS) request. In one embodiment, the client agent 120 and/orinterceptor 350 resolves the DNS request. In another embodiment, theinterceptor transmits the intercepted DNS request to the appliance 200for DNS resolution. In one embodiment, the appliance 200 resolves theDNS request and communicates the DNS response to the client agent 120.In some embodiments, the appliance 200 resolves the DNS request viaanother appliance 200′ or a DNS server 106.

In yet another embodiment, the client agent 120 may comprise two agents120 and 120′. In one embodiment, a first agent 120 may comprise aninterceptor 350 operating at the network layer of the network stack 310.In some embodiments, the first agent 120 intercepts network layerrequests such as Internet Control Message Protocol (ICMP) requests(e.g., ping and traceroute). In other embodiments, the second agent 120′may operate at the transport layer and intercept transport layercommunications. In some embodiments, the first agent 120 interceptscommunications at one layer of the network stack 310 and interfaces withor communicates the intercepted communication to the second agent 120′.

The client agent 120 and/or interceptor 350 may operate at or interfacewith a protocol layer in a manner transparent to any other protocollayer of the network stack 310. For example, in one embodiment, theinterceptor 350 operates or interfaces with the transport layer of thenetwork stack 310 transparently to any protocol layer below thetransport layer, such as the network layer, and any protocol layer abovethe transport layer, such as the session, presentation or applicationlayer protocols. This allows the other protocol layers of the networkstack 310 to operate as desired and without modification for using theinterceptor 350. As such, the client agent 120 and/or interceptor 350can interface with the transport layer to secure, optimize, accelerate,route or load-balance any communications provided via any protocolcarried by the transport layer, such as any application layer protocolover TCP/IP.

Furthermore, the client agent 120 and/or interceptor may operate at orinterface with the network stack 310 in a manner transparent to anyapplication, a user of the client 102, and any other computing device,such as a server, in communications with the client 102. The clientagent 120 and/or interceptor 350 may be installed and/or executed on theclient 102 in a manner without modification of an application. In someembodiments, the user of the client 102 or a computing device incommunications with the client 102 are not aware of the existence,execution or operation of the client agent 120 and/or interceptor 350.As such, in some embodiments, the client agent 120 and/or interceptor350 is installed, executed, and/or operated transparently to anapplication, user of the client 102, another computing device, such as aserver, or any of the protocol layers above and/or below the protocollayer interfaced to by the interceptor 350.

The client agent 120 includes an acceleration program 302, a streamingclient 306, a collection agent 304, and/or monitoring agent 197. In oneembodiment, the client agent 120 comprises an Independent ComputingArchitecture (ICA) client, or any portion thereof, developed by CitrixSystems, Inc. of Fort Lauderdale, Fla., and is also referred to as anICA client. In some embodiments, the client 120 comprises an applicationstreaming client 306 for streaming an application from a server 106 to aclient 102. In some embodiments, the client agent 120 comprises anacceleration program 302 for accelerating communications between client102 and server 106. In another embodiment, the client agent 120 includesa collection agent 304 for performing end-point detection/scanning andcollecting end-point information for the appliance 200 and/or server106.

In some embodiments, the acceleration program 302 comprises aclient-side acceleration program for performing one or more accelerationtechniques to accelerate, enhance or otherwise improve a client'scommunications with and/or access to a server 106, such as accessing anapplication provided by a server 106. The logic, functions, and/oroperations of the executable instructions of the acceleration program302 may perform one or more of the following acceleration techniques: 1)multi-protocol compression, 2) transport control protocol pooling, 3)transport control protocol multiplexing, 4) transport control protocolbuffering, and 5) caching via a cache manager. Additionally, theacceleration program 302 may perform encryption and/or decryption of anycommunications received and/or transmitted by the client 102. In someembodiments, the acceleration program 302 performs one or more of theacceleration techniques in an integrated manner or fashion.Additionally, the acceleration program 302 can perform compression onany of the protocols, or multiple-protocols, carried as a payload of anetwork packet of the transport layer protocol. The streaming client 306comprises an application, program, process, service, task or executableinstructions for receiving and executing a streamed application from aserver 106. A server 106 may stream one or more application data filesto the streaming client 306 for playing, executing or otherwise causingto be executed the application on the client 102. In some embodiments,the server 106 transmits a set of compressed or packaged applicationdata files to the streaming client 306. In some embodiments, theplurality of application files are compressed and stored on a fileserver within an archive file such as a CAB, ZIP, SIT, TAR, JAR or otherarchive. In one embodiment, the server 106 decompresses, unpackages orunarchives the application files and transmits the files to the client102. In another embodiment, the client 102 decompresses, unpackages orunarchives the application files. The streaming client 306 dynamicallyinstalls the application, or portion thereof, and executes theapplication. In one embodiment, the streaming client 306 may be anexecutable program. In some embodiments, the streaming client 306 may beable to launch another executable program.

The collection agent 304 comprises an application, program, process,service, task or executable instructions for identifying, obtainingand/or collecting information about the client 102. In some embodiments,the appliance 200 transmits the collection agent 304 to the client 102or client agent 120. The collection agent 304 may be configuredaccording to one or more policies of the policy engine 236 of theappliance. In other embodiments, the collection agent 304 transmitscollected information on the client 102 to the appliance 200. In oneembodiment, the policy engine 236 of the appliance 200 uses thecollected information to determine and provide access, authenticationand authorization control of the client's connection to a network 104.

In one embodiment, the collection agent 304 comprises an end-pointdetection and scanning mechanism, which identifies and determines one ormore attributes or characteristics of the client. For example, thecollection agent 304 may identify and determine any one or more of thefollowing client-side attributes: 1) the operating system an/or aversion of an operating system, 2) a service pack of the operatingsystem, 3) a running service, 4) a running process, and 5) a file. Thecollection agent 304 may also identify and determine the presence orversions of any one or more of the following on the client: 1) antivirussoftware, 2) personal firewall software, 3) anti-spam software, and 4)internet security software. The policy engine 236 may have one or morepolicies based on any one or more of the attributes or characteristicsof the client or client-side attributes.

In some embodiments, the client agent 120 includes a monitoring agent197 as discussed in conjunction with FIGS. 1D and 2B. The monitoringagent 197 may be any type and form of script, such as Visual Basic orJava script. In one embodiment, the monitoring agent 197 monitors andmeasures performance of any portion of the client agent 120. Forexample, in some embodiments, the monitoring agent 197 monitors andmeasures performance of the acceleration program 302. In anotherembodiment, the monitoring agent 197 monitors and measures performanceof the streaming client 306. In other embodiments, the monitoring agent197 monitors and measures performance of the collection agent 304. Instill another embodiment, the monitoring agent 197 monitors and measuresperformance of the interceptor 350. In some embodiments, the monitoringagent 197 monitors and measures any resource of the client 102, such asmemory, CPU and disk.

The monitoring agent 197 may monitor and measure performance of anyapplication of the client. In one embodiment, the monitoring agent 197monitors and measures performance of a browser on the client 102. Insome embodiments, the monitoring agent 197 monitors and measuresperformance of any application delivered via the client agent 120. Inother embodiments, the monitoring agent 197 measures and monitors enduser response times for an application, such as web-based or HTTPresponse times. The monitoring agent 197 may monitor and measureperformance of an ICA or RDP client. In another embodiment, themonitoring agent 197 measures and monitors metrics for a user session orapplication session. In some embodiments, monitoring agent 197 measuresand monitors an ICA or RDP session. In one embodiment, the monitoringagent 197 measures and monitors the performance of the appliance 200 inaccelerating delivery of an application and/or data to the client 102.

In some embodiments, and still referring to FIG. 3, a first program 322may be used to install and/or execute the client agent 120, or portionthereof, such as the interceptor 350, automatically, silently,transparently, or otherwise. In one embodiment, the first program 322comprises a plugin component, such an ActiveX control or Java control orscript that is loaded into and executed by an application. For example,the first program comprises an ActiveX control loaded and run by a webbrowser application, such as in the memory space or context of theapplication. In another embodiment, the first program 322 comprises aset of executable instructions loaded into and run by the application,such as a browser. In one embodiment, the first program 322 comprises adesigned and constructed program to install the client agent 120. Insome embodiments, the first program 322 obtains, downloads, or receivesthe client agent 120 via the network from another computing device. Inanother embodiment, the first program 322 is an installer program or aplug and play manager for installing programs, such as network drivers,on the operating system of the client 102.

D. Systems and Methods for Providing Virtualized Application DeliveryController

Referring now to FIG. 4A, a block diagram depicts one embodiment of avirtualization environment 400. In brief overview, a computing device100 includes a hypervisor layer, a virtualization layer, and a hardwarelayer. The hypervisor layer includes a hypervisor 401 (also referred toas a virtualization manager) that allocates and manages access to anumber of physical resources in the hardware layer (e.g., theprocessor(s) 421, and disk(s) 428) by at least one virtual machineexecuting in the virtualization layer. A hypervisor 401 may providevirtual resources to any number of guest operating systems 410 a, 410 b(generally 410). The virtualization layer includes at least oneoperating system 410 and a plurality of virtual resources allocated tothe at least one operating system 410. Virtual resources may include,without limitation, a plurality of virtual processors 432 a, 432 b, 432c (generally 432), and virtual disks 442 a, 442 b, 442 c (generally442), as well as virtual resources such as virtual memory and virtualnetwork interfaces. The plurality of virtual resources and the operatingsystem 410 may be referred to as a virtual machine 406. A virtualmachine 406 may include a control operating system 405 in communicationwith the hypervisor 401 and used to execute applications for managingand configuring other virtual machines on the computing device 100.

In greater detail, a hypervisor 401 may provide virtual resources to anoperating system in any manner which simulates the operating systemhaving access to a physical device. In some embodiments, a computingdevice 100 executes one or more types of hypervisors. In theseembodiments, hypervisors may be used to emulate virtual hardware,partition physical hardware, virtualize physical hardware, and executevirtual machines that provide access to computing environments.Hypervisors may include those manufactured by VMWare, Inc., of PaloAlto, Calif.; the XEN hypervisor, an open source product whosedevelopment is overseen by the open source Xen.org community; HyperV,VirtualServer or virtual PC hypervisors provided by Microsoft, orothers. In some embodiments, a computing device 100 executing ahypervisor that creates a virtual machine platform on which guestoperating systems may execute is referred to as a host server. In one ofthese embodiments, for example, the computing device 100 is a XEN SERVERprovided by Citrix Systems, Inc., of Fort Lauderdale, Fla.

In some embodiments, a hypervisor 401 executes within an operatingsystem executing on a computing device. In one of these embodiments, acomputing device executing an operating system and a hypervisor 401 maybe said to have a host operating system (the operating system executingon the computing device), and a guest operating system (an operatingsystem executing within a computing resource partition provided by thehypervisor 401). In other embodiments, a hypervisor 401 interactsdirectly with hardware on a computing device, instead of executing on ahost operating system. In one of these embodiments, the hypervisor 401may be said to be executing on “bare metal,” referring to the hardwarecomprising the computing device.

In some embodiments, a hypervisor 401 may create a virtual machine 406a-c (generally 406) in which an operating system 410 executes. In one ofthese embodiments, for example, the hypervisor 401 loads a virtualmachine image to create a virtual machine 406. In another of theseembodiments, the hypervisor 401 executes an operating system 410 withinthe virtual machine 406. In still another of these embodiments, thevirtual machine 406 executes an operating system 410.

In some embodiments, the hypervisor 401 controls processor schedulingand memory partitioning for a virtual machine 406 executing on thecomputing device 100. In one of these embodiments, the hypervisor 401controls the execution of at least one virtual machine 406. In anotherof these embodiments, the hypervisor 401 presents at least one virtualmachine 406 with an abstraction of at least one hardware resourceprovided by the computing device 100. In other embodiments, thehypervisor 401 controls whether and how physical processor capabilitiesare presented to the virtual machine 406.

A control operating system 405 may execute at least one application formanaging and configuring the guest operating systems. In one embodiment,the control operating system 405 may execute an administrativeapplication, such as an application including a user interface providingadministrators with access to functionality for managing the executionof a virtual machine, including functionality for executing a virtualmachine, terminating an execution of a virtual machine, or identifying atype of physical resource for allocation to the virtual machine. Inanother embodiment, the hypervisor 401 executes the control operatingsystem 405 within a virtual machine 406 created by the hypervisor 401.In still another embodiment, the control operating system 405 executesin a virtual machine 406 that is authorized to directly access physicalresources on the computing device 100. In some embodiments, a controloperating system 405 a on a computing device 100 a may exchange datawith a control operating system 405 b on a computing device 100 b, viacommunications between a hypervisor 401 a and a hypervisor 401 b. Inthis way, one or more computing devices 100 may exchange data with oneor more of the other computing devices 100 regarding processors andother physical resources available in a pool of resources. In one ofthese embodiments, this functionality allows a hypervisor to manage apool of resources distributed across a plurality of physical computingdevices. In another of these embodiments, multiple hypervisors manageone or more of the guest operating systems executed on one of thecomputing devices 100.

In one embodiment, the control operating system 405 executes in avirtual machine 406 that is authorized to interact with at least oneguest operating system 410. In another embodiment, a guest operatingsystem 410 communicates with the control operating system 405 via thehypervisor 401 in order to request access to a disk or a network. Instill another embodiment, the guest operating system 410 and the controloperating system 405 may communicate via a communication channelestablished by the hypervisor 401, such as, for example, via a pluralityof shared memory pages made available by the hypervisor 401.

In some embodiments, the control operating system 405 includes a networkback-end driver for communicating directly with networking hardwareprovided by the computing device 100. In one of these embodiments, thenetwork back-end driver processes at least one virtual machine requestfrom at least one guest operating system 110. In other embodiments, thecontrol operating system 405 includes a block back-end driver forcommunicating with a storage element on the computing device 100. In oneof these embodiments, the block back-end driver reads and writes datafrom the storage element based upon at least one request received from aguest operating system 410.

In one embodiment, the control operating system 405 includes a toolsstack 404. In another embodiment, a tools stack 404 providesfunctionality for interacting with the hypervisor 401, communicatingwith other control operating systems 405 (for example, on a secondcomputing device 100 b), or managing virtual machines 406 b, 406 c onthe computing device 100. In another embodiment, the tools stack 404includes customized applications for providing improved managementfunctionality to an administrator of a virtual machine farm. In someembodiments, at least one of the tools stack 404 and the controloperating system 405 include a management API that provides an interfacefor remotely configuring and controlling virtual machines 406 running ona computing device 100. In other embodiments, the control operatingsystem 405 communicates with the hypervisor 401 through the tools stack404.

In one embodiment, the hypervisor 401 executes a guest operating system410 within a virtual machine 406 created by the hypervisor 401. Inanother embodiment, the guest operating system 410 provides a user ofthe computing device 100 with access to resources within a computingenvironment. In still another embodiment, a resource includes a program,an application, a document, a file, a plurality of applications, aplurality of files, an executable program file, a desktop environment, acomputing environment, or other resource made available to a user of thecomputing device 100. In yet another embodiment, the resource may bedelivered to the computing device 100 via a plurality of access methodsincluding, but not limited to, conventional installation directly on thecomputing device 100, delivery to the computing device 100 via a methodfor application streaming, delivery to the computing device 100 ofoutput data generated by an execution of the resource on a secondcomputing device 100′ and communicated to the computing device 100 via apresentation layer protocol, delivery to the computing device 100 ofoutput data generated by an execution of the resource via a virtualmachine executing on a second computing device 100′, or execution from aremovable storage device connected to the computing device 100, such asa USB device, or via a virtual machine executing on the computing device100 and generating output data. In some embodiments, the computingdevice 100 transmits output data generated by the execution of theresource to another computing device 100′.

In one embodiment, the guest operating system 410, in conjunction withthe virtual machine on which it executes, forms a fully-virtualizedvirtual machine which is not aware that it is a virtual machine; such amachine may be referred to as a “Domain U HVM (Hardware Virtual Machine)virtual machine”. In another embodiment, a fully-virtualized machineincludes software emulating a Basic Input/Output System (BIOS) in orderto execute an operating system within the fully-virtualized machine. Instill another embodiment, a fully-virtualized machine may include adriver that provides functionality by communicating with the hypervisor401. In such an embodiment, the driver may be aware that it executeswithin a virtualized environment. In another embodiment, the guestoperating system 410, in conjunction with the virtual machine on whichit executes, forms a paravirtualized virtual machine, which is awarethat it is a virtual machine; such a machine may be referred to as a“Domain U PV virtual machine”. In another embodiment, a paravirtualizedmachine includes additional drivers that a fully-virtualized machinedoes not include. In still another embodiment, the paravirtualizedmachine includes the network back-end driver and the block back-enddriver included in a control operating system 405, as described above.

Referring now to FIG. 4B, a block diagram depicts one embodiment of aplurality of networked computing devices in a system in which at leastone physical host executes a virtual machine. In brief overview, thesystem includes a management component 404 and a hypervisor 401. Thesystem includes a plurality of computing devices 100, a plurality ofvirtual machines 406, a plurality of hypervisors 401, a plurality ofmanagement components referred to variously as tools stacks 404 ormanagement components 404, and a physical resource 421, 428. Theplurality of physical machines 100 may each be provided as computingdevices 100, described above in connection with FIGS. 1E-1H and 4A.

In greater detail, a physical disk 428 is provided by a computing device100 and stores at least a portion of a virtual disk 442. In someembodiments, a virtual disk 442 is associated with a plurality ofphysical disks 428. In one of these embodiments, one or more computingdevices 100 may exchange data with one or more of the other computingdevices 100 regarding processors and other physical resources availablein a pool of resources, allowing a hypervisor to manage a pool ofresources distributed across a plurality of physical computing devices.In some embodiments, a computing device 100 on which a virtual machine406 executes is referred to as a physical host 100 or as a host machine100.

The hypervisor executes on a processor on the computing device 100. Thehypervisor allocates, to a virtual disk, an amount of access to thephysical disk. In one embodiment, the hypervisor 401 allocates an amountof space on the physical disk. In another embodiment, the hypervisor 401allocates a plurality of pages on the physical disk. In someembodiments, the hypervisor provisions the virtual disk 442 as part of aprocess of initializing and executing a virtual machine 450.

In one embodiment, the management component 404 a is referred to as apool management component 404 a. In another embodiment, a managementoperating system 405 a, which may be referred to as a control operatingsystem 405 a, includes the management component. In some embodiments,the management component is referred to as a tools stack. In one ofthese embodiments, the management component is the tools stack 404described above in connection with FIG. 4A. In other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, an identification of a virtual machine406 to provision and/or execute. In still other embodiments, themanagement component 404 provides a user interface for receiving, from auser such as an administrator, the request for migration of a virtualmachine 406 b from one physical machine 100 to another. In furtherembodiments, the management component 404 a identifies a computingdevice 100 b on which to execute a requested virtual machine 406 d andinstructs the hypervisor 401 b on the identified computing device 100 bto execute the identified virtual machine; such a management componentmay be referred to as a pool management component.

Referring now to FIG. 4C, a diagram of an embodiment of a virtualappliance 450 operating on a hypervisor 401 of a server 106 is depicted.In brief overview, any of the functionality and/or embodiments of theappliance 200 (e.g., an application delivery controller) described abovein connection with FIGS. 2A and 2B may be deployed in any embodiment ofthe virtualized environment described above in connection with FIGS. 4Aand 4B. Instead of the functionality of the application deliverycontroller being deployed in the form of an appliance 200, suchfunctionality may be deployed in a virtualized environment 400 on anycomputing device 100, such as a client 102, server 106 or appliance 200.

As with the appliance 200 of FIGS. 2A and 2B, the virtual appliance 450may provide functionality for availability, performance, offload andsecurity. For availability, the virtual appliance may perform loadbalancing between layers 4 and 7 of the network and may also performintelligent service health monitoring. For performance increases vianetwork traffic acceleration, the virtual appliance may perform cachingand compression. To offload processing of any servers, the virtualappliance may perform connection multiplexing and pooling and/or SSLprocessing. For security, the virtual appliance may perform any of theapplication firewall functionality and SSL VPN function of appliance200.

Any of the modules of the appliance 200 as described in connection withFIGS. 2A may be packaged, combined, designed or constructed in a form ofthe virtualized appliance delivery controller 450 deployable as one ormore software modules or components executable in a virtualizedenvironment 300 or non-virtualized environment on any server, such as anoff the shelf server. For example, the virtual appliance may be providedin the form of an installation package to install on a computing device.With reference to FIG. 2A, any of the cache manager 232, policy engine236, compression 238, encryption engine 234, packet engine 240, GUI 210,CLI 212, shell services 214 and health monitoring programs 216 may bedesigned and constructed as a software component or module to run on anyoperating system of a computing device and/or of a virtualizedenvironment 300. Instead of using the encryption processor 260,processor 262, memory 264 and network stack 267 of the appliance 200,the virtualized appliance 400 may use any of these resources as providedby the virtualized environment 400 or as otherwise available on theserver 106.

Still referring to FIG. 4C, and in brief overview, any one or morevServers 275A-275N may be in operation or executed in a virtualizedenvironment 400 of any type of computing device 100, such as any server106. Any of the modules or functionality of the appliance 200 describedin connection with FIG. 2B may be designed and constructed to operate ineither a virtualized or non-virtualized environment of a server. Any ofthe vServer 275, SSL VPN 280, Intranet UP 282, Switching 284, DNS 286,acceleration 288, App FW 290 and monitoring agent may be packaged,combined, designed or constructed in a form of application deliverycontroller 450 deployable as one or more software modules or componentsexecutable on a device and/or virtualized environment 400.

In some embodiments, a server may execute multiple virtual machines 406a-406 n in the virtualization environment with each virtual machinerunning the same or different embodiments of the virtual applicationdelivery controller 450. In some embodiments, the server may execute oneor more virtual appliances 450 on one or more virtual machines on a coreof a multi-core processing system. In some embodiments, the server mayexecute one or more virtual appliances 450 on one or more virtualmachines on each processor of a multiple processor device.

E. Systems and Methods for Providing A Multi-Core Architecture

In accordance with Moore's Law, the number of transistors that may beplaced on an integrated circuit may double approximately every twoyears. However, CPU speed increases may reach plateaus, for example CPUspeed has been around 3.5-4 GHz range since 2005. In some cases, CPUmanufacturers may not rely on CPU speed increases to gain additionalperformance. Some CPU manufacturers may add additional cores to theirprocessors to provide additional performance. Products, such as those ofsoftware and networking vendors, that rely on CPUs for performance gainsmay improve their performance by leveraging these multi-core CPUs. Thesoftware designed and constructed for a single CPU may be redesignedand/or rewritten to take advantage of a multi-threaded, parallelarchitecture or otherwise a multi-core architecture.

A multi-core architecture of the appliance 200, referred to as nCore ormulti-core technology, allows the appliance in some embodiments to breakthe single core performance barrier and to leverage the power ofmulti-core CPUs. In the previous architecture described in connectionwith FIG. 2A, a single network or packet engine is run. The multiplecores of the nCore technology and architecture allow multiple packetengines to run concurrently and/or in parallel. With a packet enginerunning on each core, the appliance architecture leverages theprocessing capacity of additional cores. In some embodiments, thisprovides up to a 7× increase in performance and scalability.

Illustrated in FIG. 5A are some embodiments of work, task, load ornetwork traffic distribution across one or more processor coresaccording to a type of parallelism or parallel computing scheme, such asfunctional parallelism, data parallelism or flow-based data parallelism.In brief overview, FIG. 5A illustrates embodiments of a multi-coresystem such as an appliance 200′ with n-cores, a total of cores numbers1 through N. In one embodiment, work, load or network traffic can bedistributed among a first core 505A, a second core 505B, a third core505C, a fourth core 505D, a fifth core 505E, a sixth core 505F, aseventh core 505G, and so on such that distribution is across all or twoor more of the n cores 505N (hereinafter referred to collectively ascores 505.) There may be multiple virtual internet protocol servers(VIPs) 275 each running on a respective core of the plurality of cores.There may be multiple packet engines 240 each running on a respectivecore of the plurality of cores. Any of the approaches used may lead todifferent, varying or similar work load or performance level 515 acrossany of the cores. For a functional parallelism approach, each core mayrun a different function of the functionalities provided by the packetengine, a VIP 275 or appliance 200. In a data parallelism approach, datamay be paralleled or distributed across the cores based on the NetworkInterface Card (NIC) or VIP 275 receiving the data. In another dataparallelism approach, processing may be distributed across the cores bydistributing data flows to each core.

In further detail to FIG. 5A, in some embodiments, load, work or networktraffic can be distributed among cores 505 according to functionalparallelism 500. Functional parallelism may be based on each coreperforming one or more respective functions. In some embodiments, afirst core may perform a first function while a second core performs asecond function. In functional parallelism approach, the functions to beperformed by the multi-core system are divided and distributed to eachcore according to functionality. In some embodiments, functionalparallelism may be referred to as task parallelism and may be achievedwhen each processor or core executes a different process or function onthe same or different data. The core or processor may execute the sameor different code. In some cases, different execution threads or codemay communicate with one another as they work. Communication may takeplace to pass data from one thread to the next as part of a workflow.

In some embodiments, distributing work across the cores 505 according tofunctional parallelism 500, can comprise distributing network trafficaccording to a particular function such as network input/outputmanagement (NW I/O) 510A, secure sockets layer (SSL) encryption anddecryption 510B and transmission control protocol (TCP) functions 510C.This may lead to a work, performance or computing load 515 based on avolume or level of functionality being used. In some embodiments,distributing work across the cores 505 according to data parallelism540, can comprise distributing an amount of work 515 based ondistributing data associated with a particular hardware or softwarecomponent. In some embodiments, distributing work across the cores 505according to flow-based data parallelism 520, can comprise distributingdata based on a context or flow such that the amount of work 515A-N oneach core may be similar, substantially equal or relatively evenlydistributed.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine or VIP of the appliance.For example, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this approach, the work acrossthe cores may be divided by function in either a coarse-grained orfine-grained manner. In some cases, as illustrated in FIG. 5A, divisionby function may lead to different cores running at different levels ofperformance or load 515.

In the case of the functional parallelism approach, each core may beconfigured to run one or more functionalities of the plurality offunctionalities provided by the packet engine of the appliance. Forexample, core 1 may perform network I/O processing for the appliance200′ while core 2 performs TCP connection management for the appliance.Likewise, core 3 may perform SSL offloading while core 4 may performlayer 7 or application layer processing and traffic management. Each ofthe cores may perform the same function or different functions. Each ofthe cores may perform more than one function. Any of the cores may runany of the functionality or portions thereof identified and/or describedin conjunction with FIGS. 2A and 2B. In this approach, the work acrossthe cores may be divided by function in either a coarse-grained orfine-grained manner. In some cases, as illustrated in FIG. 5A divisionby function may lead to different cores running at different levels ofload or performance.

The functionality or tasks may be distributed in any arrangement andscheme. For example, FIG. 5B illustrates a first core, Core 1 505A,processing applications and processes associated with network I/Ofunctionality 510A. Network traffic associated with network I/O, in someembodiments, can be associated with a particular port number. Thus,outgoing and incoming packets having a port destination associated withNW I/O 510A will be directed towards Core 1 505A which is dedicated tohandling all network traffic associated with the NW I/O port. Similarly,Core 2 505B is dedicated to handling functionality associated with SSLprocessing and Core 4 505D may be dedicated handling all TCP levelprocessing and functionality.

While FIG. 5A illustrates functions such as network I/O, SSL and TCP,other functions can be assigned to cores. These other functions caninclude any one or more of the functions or operations described herein.For example, any of the functions described in conjunction with FIGS. 2Aand 2B may be distributed across the cores on a functionality basis. Insome cases, a first VIP 275A may run on a first core while a second VIP275B with a different configuration may run on a second core. In someembodiments, each core 505 can handle a particular functionality suchthat each core 505 can handle the processing associated with thatparticular function. For example, Core 2 505B may handle SSL offloadingwhile Core 4 505D may handle application layer processing and trafficmanagement.

In other embodiments, work, load or network traffic may be distributedamong cores 505 according to any type and form of data parallelism 540.In some embodiments, data parallelism may be achieved in a multi-coresystem by each core performing the same task or functionally ondifferent pieces of distributed data. In some embodiments, a singleexecution thread or code controls operations on all pieces of data. Inother embodiments, different threads or instructions control theoperation, but may execute the same code. In some embodiments, dataparallelism is achieved from the perspective of a packet engine,vServers (VIPs) 275A-C, network interface cards (NIC) 542D-E and/or anyother networking hardware or software included on or associated with anappliance 200. For example, each core may run the same packet engine orVIP code or configuration but operate on different sets of distributeddata. Each networking hardware or software construct can receivedifferent, varying or substantially the same amount of data, and as aresult may have varying, different or relatively the same amount of load515.

In the case of a data parallelism approach, the work may be divided upand distributed based on VIPs, NICs and/or data flows of the VIPs orNICs. In one of these approaches, the work of the multi-core system maybe divided or distributed among the VIPs by having each VIP work on adistributed set of data. For example, each core may be configured to runone or more VIPs. Network traffic may be distributed to the core foreach VIP handling that traffic. In another of these approaches, the workof the appliance may be divided or distributed among the cores based onwhich NIC receives the network traffic. For example, network traffic ofa first NIC may be distributed to a first core while network traffic ofa second NIC may be distributed to a second core. In some cases, a coremay process data from multiple NICs.

While FIG. 5A illustrates a single vServer associated with a single core505, as is the case for VIP1 275A, VIP2 275B and VIP3 275C. In someembodiments, a single vServer can be associated with one or more cores505. In contrast, one or more vServers can be associated with a singlecore 505. Associating a vServer with a core 505 may include that core505 to process all functions associated with that particular vServer. Insome embodiments, each core executes a VIP having the same code andconfiguration. In other embodiments, each core executes a VIP having thesame code but different configuration. In some embodiments, each coreexecutes a VIP having different code and the same or differentconfiguration.

Like vServers, NICs can also be associated with particular cores 505. Inmany embodiments, NICs can be connected to one or more cores 505 suchthat when a NIC receives or transmits data packets, a particular core505 handles the processing involved with receiving and transmitting thedata packets. In one embodiment, a single NIC can be associated with asingle core 505, as is the case with NIC1 542D and NIC2 542E. In otherembodiments, one or more NICs can be associated with a single core 505.In other embodiments, a single NIC can be associated with one or morecores 505. In these embodiments, load could be distributed amongst theone or more cores 505 such that each core 505 processes a substantiallysimilar amount of load. A core 505 associated with a NIC may process allfunctions and/or data associated with that particular NIC.

While distributing work across cores based on data of VIPs or NICs mayhave a level of independency, in some embodiments, this may lead tounbalanced use of cores as illustrated by the varying loads 515 of FIG.5A.

In some embodiments, load, work or network traffic can be distributedamong cores 505 based on any type and form of data flow. In another ofthese approaches, the work may be divided or distributed among coresbased on data flows. For example, network traffic between a client and aserver traversing the appliance may be distributed to and processed byone core of the plurality of cores. In some cases, the core initiallyestablishing the session or connection may be the core for which networktraffic for that session or connection is distributed. In someembodiments, the data flow is based on any unit or portion of networktraffic, such as a transaction, a request/response communication ortraffic originating from an application on a client. In this manner andin some embodiments, data flows between clients and servers traversingthe appliance 200′ may be distributed in a more balanced manner than theother approaches.

In flow-based data parallelism 520, distribution of data is related toany type of flow of data, such as request/response pairings,transactions, sessions, connections or application communications. Forexample, network traffic between a client and a server traversing theappliance may be distributed to and processed by one core of theplurality of cores. In some cases, the core initially establishing thesession or connection may be the core for which network traffic for thatsession or connection is distributed. The distribution of data flow maybe such that each core 505 carries a substantially equal or relativelyevenly distributed amount of load, data or network traffic.

In some embodiments, the data flow is based on any unit or portion ofnetwork traffic, such as a transaction, a request/response communicationor traffic originating from an application on a client. In this mannerand in some embodiments, data flows between clients and serverstraversing the appliance 200′ may be distributed in a more balancedmanner than the other approaches. In one embodiment, data flow can bedistributed based on a transaction or a series of transactions. Thistransaction, in some embodiments, can be between a client and a serverand can be characterized by an IP address or other packet identifier.For example, Core 1 505A can be dedicated to transactions between aparticular client and a particular server, therefore the load 515A onCore 1 505A may be comprised of the network traffic associated with thetransactions between the particular client and server. Allocating thenetwork traffic to Core 1 505A can be accomplished by routing all datapackets originating from either the particular client or server to Core1 505A.

While work or load can be distributed to the cores based in part ontransactions, in other embodiments load or work can be allocated on aper packet basis. In these embodiments, the appliance 200 can interceptdata packets and allocate them to a core 505 having the least amount ofload. For example, the appliance 200 could allocate a first incomingdata packet to Core 1 505A because the load 515A on Core 1 is less thanthe load 515B-N on the rest of the cores 505B-N. Once the first datapacket is allocated to Core 1 505A, the amount of load 515A on Core 1505A is increased proportional to the amount of processing resourcesneeded to process the first data packet. When the appliance 200intercepts a second data packet, the appliance 200 will allocate theload to Core 4 505D because Core 4 505D has the second least amount ofload. Allocating data packets to the core with the least amount of loadcan, in some embodiments, ensure that the load 515A-N distributed toeach core 505 remains substantially equal.

In other embodiments, load can be allocated on a per unit basis where asection of network traffic is allocated to a particular core 505. Theabove-mentioned example illustrates load balancing on a per packetbasis. In other embodiments, load can be allocated based on a number ofpackets such that every 10, 100 or 1000 packets are allocated to thecore 505 having the least amount of load. The number of packetsallocated to a core 505 can be a number determined by an application,user or administrator and can be any number greater than zero. In stillother embodiments, load can be allocated based on a time metric suchthat packets are distributed to a particular core 505 for apredetermined amount of time. In these embodiments, packets can bedistributed to a particular core 505 for five milliseconds or for anyperiod of time determined by a user, program, system, administrator orotherwise. After the predetermined time period elapses, data packets aretransmitted to a different core 505 for the predetermined period oftime.

Flow-based data parallelism methods for distributing work, load ornetwork traffic among the one or more cores 505 can comprise anycombination of the above-mentioned embodiments. These methods can becarried out by any part of the appliance 200, by an application or setof executable instructions executing on one of the cores 505, such asthe packet engine, or by any application, program or agent executing ona computing device in communication with the appliance 200.

The functional and data parallelism computing schemes illustrated inFIG. 5A can be combined in any manner to generate a hybrid parallelismor distributed processing scheme that encompasses function parallelism500, data parallelism 540, flow-based data parallelism 520 or anyportions thereof. In some cases, the multi-core system may use any typeand form of load balancing schemes to distribute load among the one ormore cores 505. The load balancing scheme may be used in any combinationwith any of the functional and data parallelism schemes or combinationsthereof.

Illustrated in FIG. 5B is an embodiment of a multi-core system 545,which may be any type and form of one or more systems, appliances,devices or components. This system 545, in some embodiments, can beincluded within an appliance 200 having one or more processing cores505A-N. The system 545 can further include one or more packet engines(PE) or packet processing engines (PPE) 548A-N communicating with amemory bus 556. The memory bus may be used to communicate with the oneor more processing cores 505A-N. Also included within the system 545 canbe one or more network interface cards (NIC) 552 and a flow distributor550 which can further communicate with the one or more processing cores505A-N. The flow distributor 550 can comprise a Receive Side Scaler(RSS) or Receive Side Scaling (RSS) module 560.

Further referring to FIG. 5B, and in more detail, in one embodiment thepacket engine(s) 548A-N can comprise any portion of the appliance 200described herein, such as any portion of the appliance described inFIGS. 2A and 2B. The packet engine(s) 548A-N can, in some embodiments,comprise any of the following elements: the packet engine 240, a networkstack 267; a cache manager 232; a policy engine 236; a compressionengine 238; an encryption engine 234; a GUI 210; a CLI 212; shellservices 214; monitoring programs 216; and any other software orhardware element able to receive data packets from one of either thememory bus 556 or the one of more cores 505A-N. In some embodiments, thepacket engine(s) 548A-N can comprise one or more vServers 275A-N, or anyportion thereof. In other embodiments, the packet engine(s) 548A-N canprovide any combination of the following functionalities: SSL VPN 280;Intranet UP 282; switching 284; DNS 286; packet acceleration 288; App FW280; monitoring such as the monitoring provided by a monitoring agent197; functionalities associated with functioning as a TCP stack; loadbalancing; SSL offloading and processing; content switching; policyevaluation; caching; compression; encoding; decompression; decoding;application firewall functionalities; XML processing and acceleration;and SSL VPN connectivity.

The packet engine(s) 548A-N can, in some embodiments, be associated witha particular server, user, client or network. When a packet engine 548becomes associated with a particular entity, that packet engine 548 canprocess data packets associated with that entity. For example, should apacket engine 548 be associated with a first user, that packet engine548 will process and operate on packets generated by the first user, orpackets having a destination address associated with the first user.Similarly, the packet engine 548 may choose not to be associated with aparticular entity such that the packet engine 548 can process andotherwise operate on any data packets not generated by that entity ordestined for that entity.

In some instances, the packet engine(s) 548A-N can be configured tocarry out the any of the functional and/or data parallelism schemesillustrated in FIG. 5A. In these instances, the packet engine(s) 548A-Ncan distribute functions or data among the processing cores 505A-N sothat the distribution is according to the parallelism or distributionscheme. In some embodiments, a single packet engine(s) 548A-N carriesout a load balancing scheme, while in other embodiments one or morepacket engine(s) 548A-N carry out a load balancing scheme. Each core505A-N, in one embodiment, can be associated with a particular packetengine 548 such that load balancing can be carried out by the packetengine. Load balancing may in this embodiment, require that each packetengine 548A-N associated with a core 505 communicate with the otherpacket engines associated with cores so that the packet engines 548A-Ncan collectively determine where to distribute load. One embodiment ofthis process can include an arbiter that receives votes from each packetengine for load. The arbiter can distribute load to each packet engine548A-N based in part on the age of the engine's vote and in some cases apriority value associated with the current amount of load on an engine'sassociated core 505.

Any of the packet engines running on the cores may run in user mode,kernel or any combination thereof. In some embodiments, the packetengine operates as an application or program running is user orapplication space. In these embodiments, the packet engine may use anytype and form of interface to access any functionality provided by thekernel. In some embodiments, the packet engine operates in kernel modeor as part of the kernel. In some embodiments, a first portion of thepacket engine operates in user mode while a second portion of the packetengine operates in kernel mode. In some embodiments, a first packetengine on a first core executes in kernel mode while a second packetengine on a second core executes in user mode. In some embodiments, thepacket engine or any portions thereof operates on or in conjunction withthe NIC or any drivers thereof.

In some embodiments the memory bus 556 can be any type and form ofmemory or computer bus. While a single memory bus 556 is depicted inFIG. 5B, the system 545 can comprise any number of memory buses 556. Inone embodiment, each packet engine 548 can be associated with one ormore individual memory buses 556.

The NIC 552 can in some embodiments be any of the network interfacecards or mechanisms described herein. The NIC 552 can have any number ofports. The NIC can be designed and constructed to connect to any typeand form of network 104. While a single NIC 552 is illustrated, thesystem 545 can comprise any number of NICs 552. In some embodiments,each core 505A-N can be associated with one or more single NICs 552.Thus, each core 505 can be associated with a single NIC 552 dedicated toa particular core 505. The cores 505A-N can comprise any of theprocessors described herein. Further, the cores 505A-N can be configuredaccording to any of the core 505 configurations described herein. Stillfurther, the cores 505A-N can have any of the core 505 functionalitiesdescribed herein. While FIG. 5B illustrates seven cores 505A-G, anynumber of cores 505 can be included within the system 545. Inparticular, the system 545 can comprise “N” cores, where “N” is a wholenumber greater than zero.

A core may have or use memory that is allocated or assigned for use tothat core. The memory may be considered private or local memory of thatcore and only accessible by that core. A core may have or use memorythat is shared or assigned to multiple cores. The memory may beconsidered public or shared memory that is accessible by more than onecore. A core may use any combination of private and public memory. Withseparate address spaces for each core, some level of coordination iseliminated from the case of using the same address space. With aseparate address space, a core can perform work on information and datain the core's own address space without worrying about conflicts withother cores. Each packet engine may have a separate memory pool for TCPand/or SSL connections.

Further referring to FIG. 5B, any of the functionality and/orembodiments of the cores 505 described above in connection with FIG. 5Acan be deployed in any embodiment of the virtualized environmentdescribed above in connection with FIGS. 4A and 4B. Instead of thefunctionality of the cores 505 being deployed in the form of a physicalprocessor 505, such functionality may be deployed in a virtualizedenvironment 400 on any computing device 100, such as a client 102,server 106 or appliance 200. In other embodiments, instead of thefunctionality of the cores 505 being deployed in the form of anappliance or a single device, the functionality may be deployed acrossmultiple devices in any arrangement. For example, one device maycomprise two or more cores and another device may comprise two or morecores. For example, a multi-core system may include a cluster ofcomputing devices, a server farm or network of computing devices. Insome embodiments, instead of the functionality of the cores 505 beingdeployed in the form of cores, the functionality may be deployed on aplurality of processors, such as a plurality of single core processors.

In one embodiment, the cores 505 may be any type and form of processor.In some embodiments, a core can function substantially similar to anyprocessor or central processing unit described herein. In someembodiment, the cores 505 may comprise any portion of any processordescribed herein. While FIG. 5A illustrates seven cores, there can existany “N” number of cores within an appliance 200, where “N” is any wholenumber greater than one. In some embodiments, the cores 505 can beinstalled within a common appliance 200, while in other embodiments thecores 505 can be installed within one or more appliance(s) 200communicatively connected to one another. The cores 505 can in someembodiments comprise graphics processing software, while in otherembodiments the cores 505 provide general processing capabilities. Thecores 505 can be installed physically near each other and/or can becommunicatively connected to each other. The cores may be connected byany type and form of bus or subsystem physically and/or communicativelycoupled to the cores for transferring data between to, from and/orbetween the cores.

While each core 505 can comprise software for communicating with othercores, in some embodiments a core manager (not shown) can facilitatecommunication between each core 505. In some embodiments, the kernel mayprovide core management. The cores may interface or communicate witheach other using a variety of interface mechanisms. In some embodiments,core to core messaging may be used to communicate between cores, such asa first core sending a message or data to a second core via a bus orsubsystem connecting the cores. In some embodiments, cores maycommunicate via any type and form of shared memory interface. In oneembodiment, there may be one or more memory locations shared among allthe cores. In some embodiments, each core may have separate memorylocations shared with each other core. For example, a first core mayhave a first shared memory with a second core and a second share memorywith a third core. In some embodiments, cores may communicate via anytype of programming or API, such as function calls via the kernel. Insome embodiments, the operating system may recognize and supportmultiple core devices and provide interfaces and API for inter-corecommunications.

The flow distributor 550 can be any application, program, library,script, task, service, process or any type and form of executableinstructions executing on any type and form of hardware. In someembodiments, the flow distributor 550 can be any design and constructionof circuitry to perform any of the operations and functions describedherein. In some embodiments, the flow distributor distributes, forwards,routes, controls and/or manages the distribution of data packets amongthe cores 505 and/or packet engine or VIPs running on the cores. Theflow distributor 550, in some embodiments, can be referred to as aninterface master or manager. In one embodiment, the flow distributor 550comprises a set of executable instructions executing on a core orprocessor of the appliance 200. In another embodiment, the flowdistributor 550 comprises a set of executable instructions executing ona computing machine in communication with the appliance 200. In someembodiments, the flow distributor 550 comprises a set of executableinstructions executing on a NIC, such as firmware. In still otherembodiments, the flow distributor 550 comprises any combination ofsoftware and hardware to distribute data packets among cores orprocessors. In one embodiment, the flow distributor 550 executes on atleast one of the cores 505A-N, while in other embodiments a separateflow distributor 550 assigned to each core 505A-N executes on anassociated core 505A-N. The flow distributor may use any type and formof statistical or probabilistic algorithms or decision making to balancethe flows across the cores. The hardware of the appliance, such as aNIC, or the kernel may be designed and constructed to support sequentialoperations across the NICs and/or cores.

In embodiments where the system 545 comprises one or more flowdistributors 550, each flow distributor 550 can be associated with aprocessor 505 or a packet engine 548. The flow distributors 550 cancomprise an interface mechanism that allows each flow distributor 550 tocommunicate with the other flow distributors 550 executing within thesystem 545. In one instance, the one or more flow distributors 550 candetermine how to balance load by communicating with each other. Thisprocess can operate substantially similarly to the process describedabove for submitting votes to an arbiter which then determines whichflow distributor 550 should receive the load. In other embodiments, afirst flow distributor 550′ can identify the load on an associated coreand determine whether to forward a first data packet to the associatedcore based on any of the following criteria: the load on the associatedcore is above a predetermined threshold; the load on the associated coreis below a predetermined threshold; the load on the associated core isless than the load on the other cores; or any other metric that can beused to determine where to forward data packets based in part on theamount of load on a processor.

The flow distributor 550 can distribute network traffic among the cores505 according to a distribution, computing or load balancing scheme suchas those described herein. In one embodiment, the flow distributor candistribute network traffic according to any one of a functionalparallelism distribution scheme 550, a data parallelism loaddistribution scheme 540, a flow-based data parallelism distributionscheme 520, or any combination of these distribution scheme or any loadbalancing scheme for distributing load among multiple processors. Theflow distributor 550 can therefore act as a load distributor by takingin data packets and distributing them across the processors according toan operative load balancing or distribution scheme. In one embodiment,the flow distributor 550 can comprise one or more operations, functionsor logic to determine how to distribute packers, work or loadaccordingly. In still other embodiments, the flow distributor 550 cancomprise one or more sub operations, functions or logic that canidentify a source address and a destination address associated with adata packet, and distribute packets accordingly.

In some embodiments, the flow distributor 550 can comprise areceive-side scaling (RSS) network driver module or any type and form ofexecutable instructions which distribute data packets among the one ormore cores 505. The RSS module can comprise any combination of hardwareand software, In some embodiments, the RSS module works in conjunctionwith the flow distributor 550 to distribute data packets across thecores 505A-N or among multiple processors in a multi-processor network.The RSS module can execute within the NIC 552 in some embodiments, andin other embodiments can execute on any one of the cores 505.

In some embodiments, the RSS module uses the MICROSOFTreceive-side-scaling (RSS) scheme. In one embodiment, RSS is a MicrosoftScalable Networking initiative technology that enables receiveprocessing to be balanced across multiple processors in the system whilemaintaining in-order delivery of the data. The RSS may use any type andform of hashing scheme to determine a core or processor for processing anetwork packet.

The RSS module can apply any type and form hash function such as theToeplitz hash function. The hash function may be applied to the hashtype or any the sequence of values. The hash function may be a securehash of any security level or is otherwise cryptographically secure. Thehash function may use a hash key. The size of the key is dependent uponthe hash function. For the Toeplitz hash, the size may be 40 bytes forIPv6 and 16 bytes for IPv4.

The hash function may be designed and constructed based on any one ormore criteria or design goals. In some embodiments, a hash function maybe used that provides an even distribution of hash result for differenthash inputs and different hash types, including TCP/IPv4, TCP/IPv6,IPv4, and IPv6 headers. In some embodiments, a hash function may be usedthat provides a hash result that is evenly distributed when a smallnumber of buckets are present (for example, two or four). In someembodiments, hash function may be used that provides a hash result thatis randomly distributed when a large number of buckets were present (forexample, 64 buckets). In some embodiments, the hash function isdetermined based on a level of computational or resource usage. In someembodiments, the hash function is determined based on ease or difficultyof implementing the hash in hardware. In some embodiments, the hashfunction is determined based on the ease or difficulty of a maliciousremote host to send packets that would all hash to the same bucket.

The RSS module may generate hashes from any type and form of input, suchas a sequence of values. This sequence of values can include any portionof the network packet, such as any header, field or payload of networkpacket, or portions thereof. In some embodiments, the input to the hashmay be referred to as a hash type and include any tuples of informationassociated with a network packet or data flow, such as any of thefollowing: a four tuple comprising at least two IP addresses and twoports; a four tuple comprising any four sets of values; a six tuple; atwo tuple; and/or any other sequence of numbers or values. The followingare example of hash types that may be used by RSS:

-   -   four-tuple of source TCP Port, source IP version 4 (IPv4)        address, destination TCP Port, and destination IPv4 address.    -   four-tuple of source TCP Port, source IP version 6 (IPv6)        address, destination TCP Port, and destination IPv6 address.    -   2-tuple of source IPv4 address, and destination IPv4 address.    -   2-tuple of source IPv6 address, and destination IPv6 address.    -   2-tuple of source IPv6 address, and destination IPv6 address,        including support for parsing IPv6 extension headers.

The hash result or any portion thereof may used to identify a core orentity, such as a packet engine or VIP, for distributing a networkpacket. In some embodiments, one or more hash bits or mask are appliedto the hash result. The hash bit or mask may be any number of bits orbytes. A NIC may support any number of bits, such as seven bits. Thenetwork stack may set the actual number of bits to be used duringinitialization. The number will be between 1 and 7, inclusive.

The hash result may be used to identify the core or entity via any typeand form of table, such as a bucket table or indirection table. In someembodiments, the number of hash-result bits are used to index into thetable. The range of the hash mask may effectively define the size of theindirection table. Any portion of the hash result or the hast resultitself may be used to index the indirection table. The values in thetable may identify any of the cores or processor, such as by a core orprocessor identifier. In some embodiments, all of the cores of themulti-core system are identified in the table. In other embodiments, aport of the cores of the multi-core system are identified in the table.The indirection table may comprise any number of buckets for example 2to 128 buckets that may be indexed by a hash mask. Each bucket maycomprise a range of index values that identify a core or processor. Insome embodiments, the flow controller and/or RSS module may rebalancethe network rebalance the network load by changing the indirectiontable.

In some embodiments, the multi-core system 545 does not include a RSSdriver or RSS module. In some of these embodiments, a software steeringmodule (not shown) or a software embodiment of the RSS module within thesystem can operate in conjunction with or as part of the flowdistributor 550 to steer packets to cores 505 within the multi-coresystem 545.

The flow distributor 550, in some embodiments, executes within anymodule or program on the appliance 200, on any one of the cores 505 andon any one of the devices or components included within the multi-coresystem 545. In some embodiments, the flow distributor 550 can execute onthe first core 505A, while in other embodiments the flow distributor 550can execute on the NIC 552. In still other embodiments, an instance ofthe flow distributor 550′ can execute on each core 505 included in themulti-core system 575. In this embodiment, each instance of the flowdistributor 550′ can communicate with other instances of the flowdistributor 550′ to forward packets back and forth across the cores 505.There exist situations where a response to a request packet may not beprocessed by the same core, i.e. the first core processes the requestwhile the second core processes the response. In these situations, theinstances of the flow distributor 550′ can intercept the packet andforward it to the desired or correct core 505, i.e. a flow distributorinstance 550′ can forward the response to the first core. Multipleinstances of the flow distributor 550′ can execute on any number ofcores 505 and any combination of cores 505.

The flow distributor may operate responsive to any one or more rules orpolicies. The rules may identify a core or packet processing engine toreceive a network packet, data or data flow. The rules may identify anytype and form of tuple information related to a network packet, such asa four-tuple of source and destination IP address and source anddestination ports. Based on a received packet matching the tuplespecified by the rule, the flow distributor may forward the packet to acore or packet engine. In some embodiments, the packet is forwarded to acore via shared memory and/or core to core messaging.

Although FIG. 5B illustrates the flow distributor 550 as executingwithin the multi-core system 545, in some embodiments the flowdistributor 550 can execute on a computing device or appliance remotelylocated from the multi-core system 545. In such an embodiment, the flowdistributor 550 can communicate with the multi-core system 545 to takein data packets and distribute the packets across the one or more cores505. The flow distributor 550 can, in one embodiment, receive datapackets destined for the appliance 200, apply a distribution scheme tothe received data packets and distribute the data packets to the one ormore cores 505 of the multi-core system 545. In one embodiment, the flowdistributor 550 can be included in a router or other appliance such thatthe router can target particular cores 505 by altering meta dataassociated with each packet so that each packet is targeted towards asub-node of the multi-core system 55. In such an embodiment, CISCO'svn-tag mechanism can be used to alter or tag each packet with theappropriate meta data.

Illustrated in FIG. 5C is an embodiment of a multi-core system 575comprising one or more processing cores 505A-N. In brief overview, oneof the cores 505 can be designated as a control core 505A and can beused as a control plane 570 for the other cores 505. The other cores maybe secondary cores which operate in a data plane while the control coreprovides the control plane. The cores 505A-N may share a global cache580. While the control core provides a control plane, the other cores inthe multi-core system form or provide a data plane. These cores performdata processing functionality on network traffic while the controlprovides initialization, configuration and control of the multi-coresystem.

Further referring to FIG. 5C, and in more detail, the cores 505A-N aswell as the control core 505A can be any processor described herein.Furthermore, the cores 505A-N and the control core 505A can be anyprocessor able to function within the system 575 described in FIG. 5C.Still further, the cores 505A-N and the control core 505A can be anycore or group of cores described herein. The control core may be adifferent type of core or processor than the other cores. In someembodiments, the control may operate a different packet engine or have apacket engine configured differently than the packet engines of theother cores.

Any portion of the memory of each of the cores may be allocated to orused for a global cache that is shared by the cores. In brief overview,a predetermined percentage or predetermined amount of each of the memoryof each core may be used for the global cache. For example, 50% of eachmemory of each code may be dedicated or allocated to the shared globalcache. That is, in the illustrated embodiment, 2 GB of each coreexcluding the control plane core or core 1 may be used to form a 28 GBshared global cache. The configuration of the control plane such as viathe configuration services may determine the amount of memory used forthe shared global cache. In some embodiments, each core may provide adifferent amount of memory for use by the global cache. In otherembodiments, any one core may not provide any memory or use the globalcache. In some embodiments, any of the cores may also have a local cachein memory not allocated to the global shared memory. Each of the coresmay store any portion of network traffic to the global shared cache.Each of the cores may check the cache for any content to use in arequest or response. Any of the cores may obtain content from the globalshared cache to use in a data flow, request or response.

The global cache 580 can be any type and form of memory or storageelement, such as any memory or storage element described herein. In someembodiments, the cores 505 may have access to a predetermined amount ofmemory (i.e. 32 GB or any other memory amount commensurate with thesystem 575). The global cache 580 can be allocated from thatpredetermined amount of memory while the rest of the available memorycan be allocated among the cores 505. In other embodiments, each core505 can have a predetermined amount of memory. The global cache 580 cancomprise an amount of the memory allocated to each core 505. This memoryamount can be measured in bytes, or can be measured as a percentage ofthe memory allocated to each core 505. Thus, the global cache 580 cancomprise 1 GB of memory from the memory associated with each core 505,or can comprise 20 percent or one-half of the memory associated witheach core 505. In some embodiments, only a portion of the cores 505provide memory to the global cache 580, while in other embodiments theglobal cache 580 can comprise memory not allocated to the cores 505.

Each core 505 can use the global cache 580 to store network traffic orcache data. In some embodiments, the packet engines of the core use theglobal cache to cache and use data stored by the plurality of packetengines. For example, the cache manager of FIG. 2A and cachefunctionality of FIG. 2B may use the global cache to share data foracceleration. For example, each of the packet engines may storeresponses, such as HTML data, to the global cache. Any of the cachemanagers operating on a core may access the global cache to servercaches responses to client requests.

In some embodiments, the cores 505 can use the global cache 580 to storea port allocation table which can be used to determine data flow basedin part on ports. In other embodiments, the cores 505 can use the globalcache 580 to store an address lookup table or any other table or listthat can be used by the flow distributor to determine where to directincoming and outgoing data packets. The cores 505 can, in someembodiments read from and write to cache 580, while in other embodimentsthe cores 505 can only read from or write to cache 580. The cores mayuse the global cache to perform core to core communications.

The global cache 580 may be sectioned into individual memory sectionswhere each section can be dedicated to a particular core 505. In oneembodiment, the control core 505A can receive a greater amount ofavailable cache, while the other cores 505 can receiving varying amountsor access to the global cache 580.

In some embodiments, the system 575 can comprise a control core 505A.While FIG. 5C illustrates core 1 505A as the control core, the controlcore can be any core within the appliance 200 or multi-core system.Further, while only a single control core is depicted, the system 575can comprise one or more control cores each having a level of controlover the system. In some embodiments, one or more control cores can eachcontrol a particular aspect of the system 575. For example, one core cancontrol deciding which distribution scheme to use, while another corecan determine the size of the global cache 580.

The control plane of the multi-core system may be the designation andconfiguration of a core as the dedicated management core or as a mastercore. This control plane core may provide control, management andcoordination of operation and functionality the plurality of cores inthe multi-core system. This control plane core may provide control,management and coordination of allocation and use of memory of thesystem among the plurality of cores in the multi-core system, includinginitialization and configuration of the same. In some embodiments, thecontrol plane includes the flow distributor for controlling theassignment of data flows to cores and the distribution of networkpackets to cores based on data flows. In some embodiments, the controlplane core runs a packet engine and in other embodiments, the controlplane core is dedicated to management and control of the other cores ofthe system.

The control core 505A can exercise a level of control over the othercores 505 such as determining how much memory should be allocated toeach core 505 or determining which core 505 should be assigned to handlea particular function or hardware/software entity. The control core505A, in some embodiments, can exercise control over those cores 505within the control plan 570. Thus, there can exist processors outside ofthe control plane 570 which are not controlled by the control core 505A.Determining the boundaries of the control plane 570 can includemaintaining, by the control core 505A or agent executing within thesystem 575, a list of those cores 505 controlled by the control core505A. The control core 505A can control any of the following:initialization of a core; determining when a core is unavailable;re-distributing load to other cores 505 when one core fails; determiningwhich distribution scheme to implement; determining which core shouldreceive network traffic; determining how much cache should be allocatedto each core; determining whether to assign a particular function orelement to a particular core; determining whether to permit cores tocommunicate with one another; determining the size of the global cache580; and any other determination of a function, configuration oroperation of the cores within the system 575.

F. Systems and Methods for Providing a Distributed Cluster Architecture

As discussed in the previous section, to overcome limitations ontransistor spacing and CPU speed increases, many CPU manufacturers haveincorporated multi-core CPUs to improve performance beyond that capableof even a single, higher speed CPU. Similar or further performance gainsmay be made by operating a plurality of appliances, either single ormulti-core, together as a distributed or clustered appliance. Individualcomputing devices or appliances may be referred to as nodes of thecluster. A centralized management system may perform load balancing,distribution, configuration, or other tasks to allow the nodes tooperate in conjunction as a single computing system. Externally or toother devices, including servers and clients, in many embodiments, thecluster may be viewed as a single virtual appliance or computing device,albeit one with performance exceeding that of a typical individualappliance.

Referring now to FIG. 6, illustrated is an embodiment of a computingdevice cluster or appliance cluster 600. A plurality of appliances 200a-200 n, or other computing devices, sometimes referred to as nodes,such as desktop computers, servers, rackmount servers, blade servers, orany other type and form of computing device may be joined into a singleappliance cluster 600. Although referred to as an appliance cluster, inmany embodiments, the cluster may operate as an application server,network storage server, backup service, or any other type of computingdevice without limitation. In many embodiments, the appliance cluster600 may be used to perform many of the functions of appliances 200, WANoptimization devices, network acceleration devices, or other devicesdiscussed above.

In some embodiments, the appliance cluster 600 may comprise a homogenousset of computing devices, such as identical appliances, blade serverswithin one or more chassis, desktop or rackmount computing devices, orother devices. In other embodiments, the appliance cluster 600 maycomprise a heterogeneous or mixed set of devices, including differentmodels of appliances, mixed appliances and servers, or any other set ofcomputing devices. This may allow for an appliance cluster 600 to beexpanded or upgraded over time with new models or devices, for example.

In some embodiments, each computing device or appliance 200 of anappliance cluster 600 may comprise a multi-core appliance, as discussedabove. In many such embodiments, the core management and flowdistribution methods discussed above may be utilized by each individualappliance, in addition to the node management and distribution methodsdiscussed herein. This may be thought of as a two-tier distributedsystem, with one appliance comprising and distributing data to multiplenodes, and each node comprising and distributing data for processing tomultiple cores. Accordingly, in such embodiments, the node distributionsystem need not manage flow distribution to individual cores, as thatmay be taken care of by a master or control core as discussed above.

In many embodiments, an appliance cluster 600 may be physically grouped,such as a plurality of blade servers in a chassis or plurality ofrackmount devices in a single rack, but in other embodiments, theappliance cluster 600 may be distributed in a plurality of chassis,plurality of racks, plurality of rooms in a data center, plurality ofdata centers, or any other physical arrangement. Accordingly, theappliance cluster 600 may be considered a virtual appliance, grouped viacommon configuration, management, and purpose, rather than a physicalgroup.

In some embodiments, an appliance cluster 600 may be connected to one ormore networks 104, 104′. For example, referring briefly back to FIG. 1A,in some embodiments, an appliance 200 may be deployed between a network104 joined to one or more clients 102, and a network 104′ joined to oneor more servers 106. An appliance cluster 600 may be similarly deployedto operate as a single appliance. In many embodiments, this may notrequire any network topology changes external to appliance cluster 600,allowing for ease of installation and scalability from a singleappliance scenario. In other embodiments, an appliance cluster 600 maybe similarly deployed as shown in FIGS. 1B-1D or discussed above. Instill other embodiments, an appliance cluster may comprise a pluralityof virtual machines or processes executed by one or more servers. Forexample, in one such embodiment, a server farm may execute a pluralityof virtual machines, each virtual machine configured as an appliance200, and a plurality of the virtual machines acting in concert as anappliance cluster 600. In yet still other embodiments, an appliancecluster 600 may comprise a mix of appliances 200 or virtual machinesconfigured as appliances 200. In some embodiments, appliance cluster 600may be geographically distributed, with the plurality of appliances 200not co-located. For example, referring back to FIG. 6, in one suchembodiment, a first appliance 200 a may be located at a first site, suchas a data center and a second appliance 200 b may be located at a secondsite, such as a central office or corporate headquarters. In a furtherembodiment, such geographically remote appliances may be joined by adedicated network, such as a T1 or T3 point-to-point connection; a VPN;or any other type and form of network. Accordingly, although there maybe additional communications latency compared to co-located appliances200 a-200 b, there may be advantages in reliability in case of sitepower failures or communications outages, scalability, or otherbenefits. In some embodiments, latency issues may be reduced throughgeographic or network-based distribution of data flows. For example,although configured as an appliance cluster 600, communications fromclients and servers at the corporate headquarters may be directed to theappliance 200 b deployed at the site, load balancing may be weighted bylocation, or similar steps can be taken to mitigate any latency.

Still referring to FIG. 6, an appliance cluster 600 may be connected toa network via a client data plane 602. In some embodiments, client dataplane 602 may comprise a communication network, such as a network 104,carrying data between clients and appliance cluster 600. In someembodiments, client data plane 602 may comprise a switch, hub, router,or other network devices bridging an external network 104 and theplurality of appliances 200 a-200 n of the appliance cluster 600. Forexample, in one such embodiment, a router may be connected to anexternal network 104, and connected to a network interface of eachappliance 200 a-200 n. In some embodiments, this router or switch may bereferred to as an interface manager or master, and may further beconfigured to distribute traffic evenly across the nodes in theapplication cluster 600. Thus, in many embodiments, the interface mastermay comprise a flow distributor external to appliance cluster 600. Inother embodiments, the interface master may comprise one of appliances200 a-200 n. For example, a first appliance 200 a may serve as theinterface master, receiving incoming traffic for the appliance cluster600 and distributing the traffic across each of appliances 200 b-200 n.In some embodiments, return traffic may similarly flow from each ofappliances 200 b-200 n via the first appliance 200 a serving as theinterface master. In other embodiments, return traffic from each ofappliances 200 b-200 n may be transmitted directly to a network 104,104′, or via an external router, switch, or other device. In someembodiments, appliances 200 of the appliance cluster not serving as aninterface master may be referred to as interface slaves.

The interface master may perform load balancing or traffic flowdistribution in any of a variety of ways. For example, in someembodiments, the interface master may comprise a router performingequal-cost multi-path (ECMP) routing with nexthops configured withappliances or nodes of the cluster. The interface master may use anopen-shortest path first (OSPF) In some embodiments, the interfacemaster may use a stateless hash-based mechanism for trafficdistribution, such as hashes based on IP address or other packetinformation tuples, as discussed above. Hash keys and/or salt may beselected for even distribution across the nodes. In other embodiments,the interface master may perform flow distribution via link aggregation(LAG) protocols, or any other type and form of flow distribution, loadbalancing, and routing.

In some embodiments, the appliance cluster 600 may be connected to anetwork via a server data plane 604. Similar to client data plane 602,server data plane 604 may comprise a communication network, such as anetwork 104′, carrying data between servers and appliance cluster 600.In some embodiments, server data plane 604 may comprise a switch, hub,router, or other network devices bridging an external network 104′ andthe plurality of appliances 200 a-200 n of the appliance cluster 600.For example, in one such embodiment, a router may be connected to anexternal network 104′, and connected to a network interface of eachappliance 200 a-200 n. In many embodiments, each appliance 200 a-200 nmay comprise multiple network interfaces, with a first network interfaceconnected to client data plane 602 and a second network interfaceconnected to server data plane 604. This may provide additional securityand prevent direct interface of client and server networks by havingappliance cluster 600 server as an intermediary device. In otherembodiments, client data plane 602 and server data plane 604 may bemerged or combined. For example, appliance cluster 600 may be deployedas a non-intermediary node on a network with clients 102 and servers106. As discussed above, in many embodiments, an interface master may bedeployed on the server data plane 604, for routing and distributingcommunications from the servers and network 104′ to each appliance ofthe appliance cluster. In many embodiments, an interface master forclient data plane 602 and an interface master for server data plane 604may be similarly configured, performing ECMP or LAG protocols asdiscussed above.

In some embodiments, each appliance 200 a-200 n in appliance cluster 600may be connected via an internal communication network or back plane606. Back plane 606 may comprise a communication network for inter-nodeor inter-appliance control and configuration messages, and forinter-node forwarding of traffic. For example, in one embodiment inwhich a first appliance 200 a communicates with a client via network104, and a second appliance 200 b communicates with a server via network104′, communications between the client and server may flow from clientto first appliance, from first appliance to second appliance via backplane 606, and from second appliance to server, and vice versa. In otherembodiments, back plane 606 may carry configuration messages, such asinterface pause or reset commands; policy updates such as filtering orcompression policies; status messages such as buffer status, throughput,or error messages; or any other type and form of inter-nodecommunication. In some embodiments, RSS keys or hash keys may be sharedby all nodes in the cluster, and may be communicated via back plane 606.For example, a first node or master node may select an RSS key, such asat startup or boot, and may distribute this key for use by other nodes.In some embodiments, back plane 606 may comprise a network betweennetwork interfaces of each appliance 200, and may comprise a router,switch, or other network device (not illustrated). Thus, in someembodiments and as discussed above, a router for client data plane 602may be deployed between appliance cluster 600 and network 104, a routerfor server data plane 604 may be deployed between appliance cluster 600and network 104′, and a router for back plane 606 may be deployed aspart of appliance cluster 600. Each router may connect to a differentnetwork interface of each appliance 200. In other embodiments, one ormore planes 602-606 may be combined, or a router or switch may be splitinto multiple LANs or VLANs to connect to different interfaces ofappliances 200 a-200 n and serve multiple routing functionssimultaneously, to reduce complexity or eliminate extra devices from thesystem.

In some embodiments, a control plane (not illustrated) may communicateconfiguration and control traffic from an administrator or user to theappliance cluster 600. In some embodiments, the control plane may be afourth physical network, while in other embodiments, the control planemay comprise a VPN, tunnel, or communication via one of planes 602-606.Thus, the control plane may, in some embodiments, be considered avirtual communication plane. In other embodiments, an administrator mayprovide configuration and control through a separate interface, such asa serial communication interface such as RS-232; a USB communicationinterface; or any other type and form of communication. In someembodiments, an appliance 200 may comprise an interface foradministration, such as a front panel with buttons and a display; a webserver for configuration via network 104, 104′ or back plane 606; or anyother type and form of interface.

In some embodiments, as discussed above, appliance cluster 600 mayinclude internal flow distribution. For example, this may be done toallow nodes to join/leave transparently to external devices. To preventan external flow distributor from needing to be repeatedly reconfiguredon such changes, a node or appliance may act as an interface master ordistributor for steering network packets to the correct node within thecluster 600. For example, in some embodiments, when a node leaves thecluster (such as on failure, reset, or similar cases), an external ECMProuter may identify the change in nodes, and may rehash all flows toredistribute traffic. This may result in dropping and resetting allconnections. The same drop and reset may occur when the node rejoins. Insome embodiments, for reliability, two appliances or nodes withinappliance cluster 600 may receive communications from external routersvia connection mirroring.

In many embodiments, flow distribution among nodes of appliance cluster600 may use any of the methods discussed above for flow distributionamong cores of an appliance. For example, in one embodiment, a masterappliance, master node, or interface master, may compute a RSS hash,such as a Toeplitz hash on incoming traffic and consult a preferencelist or distribution table for the hash. In many embodiments, the flowdistributor may provide the hash to the recipient appliance whenforwarding the traffic. This may eliminate the need for the node torecompute the hash for flow distribution to a core. In many suchembodiments, the RSS key used for calculating hashes for distributionamong the appliances may comprise the same key as that used forcalculating hashes for distribution among the cores, which may bereferred to as a global RSS key, allowing for reuse of the calculatedhash. In some embodiments, the hash may be computed with input tuples oftransport layer headers including port numbers, internet layer headersincluding IP addresses; or any other packet header information. In someembodiments, packet body information may be utilized for the hash. Forexample, in one embodiment in which traffic of one protocol isencapsulated within traffic of another protocol, such as lossy UDPtraffic encapsulated via a lossless TCP header, the flow distributor maycalculate the hash based on the headers of the encapsulated protocol(e.g. UDP headers) rather than the encapsulating protocol (e.g. TCPheaders). Similarly, in some embodiments in which packets areencapsulated and encrypted or compressed, the flow distributor maycalculate the hash based on the headers of the payload packet afterdecryption or decompression. In still other embodiments, nodes may haveinternal IP addresses, such as for configuration or administrationpurposes. Traffic to these IP addresses need not be hashed anddistributed, but rather may be forwarded to the node owning thedestination address. For example, an appliance may have a web server orother server running for configuration or administration purposes at anIP address of 1.2.3.4, and, in some embodiments, may register thisaddress with the flow distributor as it's internal IP address. In otherembodiments, the flow distributor may assign internal IP addresses toeach node within the appliance cluster 600. Traffic arriving fromexternal clients or servers, such as a workstation used by anadministrator, directed to the internal IP address of the appliance(1.2.3.4) may be forwarded directly, without requiring hashing.

G. Systems and Methods for Improving Security of SSL Communications

Secure Socket Layer (SSL) is a protocol designed to providecommunications security over a computer network. When a client deviceattempts to establish an SSL connection with a server, the server issuesan SSL certificate to the client device. Typically an SSL certificateincludes information such as the domain name, company name, and addressof the organization that owns the server. SSL certificates are issued toorganizations by a certificate authority, which should take steps toconfirm the identity of the organization applying for the certificate.Therefore, receipt of an SSL certificate is intended to provide somedegree of assurance to a client device that the server to which theclient has requested a connection is owned by a trusted organization.

Because SSL certificates are issued by certificate authorities, an SSLcertificate is only as secure as the certificate authority itself. Forexample, in some instances, a certificate authority may knowingly issuea valid certificate to the wrong party. In other instances, acertificate authority may be deceived into issuing a valid certificateto a malicious party who is impersonating a trusted organization.Therefore, mere receipt of a valid SSL certificate by a client devicecannot guarantee that the server to which the client has requested aconnection is actually owned by a trusted organization.

Furthermore, SSL communications also can be compromised by other typesof attacks. For example, in a man-in-the-middle (MITM) attack, a thirdparty intercepts communications sent from a client device to a serverand also intercepts communications sent from the server to the clientdevice. The third party impersonates the server to the client device,and impersonates the client device to the server, thereby accessing allof the information transmitted over the connection without the knowledgeof either of the client device or the server.

Thus, SSL communications are vulnerable to various forms of attack. Thisdisclosure provides methods and systems for improving security of SSLcommunications. SSL security can be improved, for example, by verifyingthat a server issuing an SSL certificate responds using an expected SSLcertificate, indicating that the certificate has not been forged, and byverifying that the connection to the server resolves to the expectedinterne protocol (IP) address, indicating that the private key has notbeen stolen. In some implementations, additional protective measuresalso may be taken. For example, SSL certificates can be analyzed todetermine whether the certificates correspond to up-to-date bestpractices in computer security. Other networking functions, such asborder gateway protocol (BGP), also can be analyzed to provideadditional measures of security.

Some existing services may simply collect data on certificate issuanceand presence—and have no definitive data on which certificate isintended to be used for a given service. By integrating the intermediarydevice with the SSL certificate observatory, the intermediary device cangain insights not previously available. By way of this disclosure, thecode hosting the SSL certificate is used to provide the web service witha service fingerprint indicating how the virtual server should appear toother devices. Further, by way of this disclosure, connections with thevirtual server can be actively validated in real-time by extending theSSL handshake.

FIG. 7A is a block diagram of an embodiment of a system 700 forimproving security of SSL communications. The system 700 includes adevice 705 in communication with at least one server 709, a web service710, and a plurality of agents 715. As shown in FIG. 7A, the device 705can be a device intermediary to a plurality of clients and a pluralityof servers, such as the appliance 200 shown in FIG. 2A. In someimplementations, the device 705 can be part of a cluster of appliances,such as the appliance cluster 600 shown in FIG. 6. It should beunderstood that, while the device 705 is illustrated as having directcommunication links to the server 709, the web service 710, and theagents 715, in some implementations, the device 705 may communicate withany of the server 709, the web service 710, and the agents 715 via oneor more additional computer networks, such as local area networks, widearea networks, or the Internet. In some implementations, the device 705and the server 709 can be included within a datacenter network. The webservice 710 and the agents 715 may be included within the samedatacenter network or may be external to the datacenter network.

FIG. 7B is a block diagram of an embodiment of the device 705 includedin the system 700 shown in FIG. 7A. As shown in FIG. 7B, the device 705includes a configuration change identifier 720, a service fingerprintgenerator 722, a secure connection interface 724, a service fingerprinttransmitter 726, a verification key generator 728, and a notificationreceiver 730. The system 700 of FIG. 7A and the device 705 of FIG. 7Bare discussed together below.

In some implementations, the system 700 also can include a plurality ofclient devices (not shown in FIG. 7A). The device 705 can managecommunications between the plurality of client devices and the server709. It should be understood that, while only a single server 709 isshown in FIG. 7A, the system 700 can include multiple servers thatcommunicate with the device 705, similar to the server 709.

In some implementations, the device 705 can be an application deliverycontroller (ADC) configured to implement a virtual server correspondingto the server 709. A virtual server is a named entity of the device 705that external clients can use to access applications hosted on theservers, such as server 709. The virtual server can be represented by analphanumeric name, virtual IP (VIP) address, port, and protocol. When aclient attempts to access applications on a server, the client sends arequest to the VIP instead of the IP address of the physical server.When the appliance receives a request at the VIP address, it terminatesthe connection at the virtual server and uses its own connection withthe server on behalf of the client. The port and protocol settings ofthe virtual server determine the applications that the virtual serverrepresents. For example, a web server can be represented by a virtualserver and a service whose port and protocol are set to 80 and HTTP,respectively. Multiple virtual servers can use the same VIP address butdifferent protocols and ports.

Virtual servers can be configured to enable networking features. Mostfeatures, like compression, caching, and SSL offload, are normallyenabled on a virtual server. When the device 705 receives a request at aVIP address, the device 705 chooses the appropriate virtual server bythe port on which the request was received and its protocol. The device705 then processes the request as appropriate for the featuresconfigured on the virtual server.

In many cases, virtual servers work in tandem with services. Multipleservices can be bound to a virtual server. These services represent theapplications running on physical servers in a server farm. After thedevice 705 processes requests received at a VIP address, the device 705can forward them to the servers in accordance with one or more loadbalancing algorithms configured on the virtual server.

In some implementations, the organization that owns, manages, maintainsor utilizes the server 709 may apply for an SSL certificate, in order tofacilitate encrypted communication between the server 709 and one ormore clients. Thus, the SSL certificate of the server 709 can betransmitted through the device 705 in response to a request to establisha secure connection with the server 709. In some implementations, thedevice 705 can save a copy of the SSL certificate of the server 709.This can help to improve response times, because the device 705 canrespond to a request to establish a secure connection by transmittingthe SSL certificate to the requesting device via the secure connectioninterface 724 without the need for the server 709 to process therequest. The device 705 also can store a copy of a private key belongingto the server 709. The device 705 can use the private key of the server709 to further reduce response times, by using the private key todecrypt secure communications destined for the server 709 withoutburdening the server 709 with the computational task of performing thedecryption. In some implementations, the device 705 can store more thanone SSL certificate or more than one private key for the server 709. Insome implementations, the device 705 can store SSL certificates andprivate keys corresponding to each of a plurality of servers similar tothe server 709.

The device 705 can include the service fingerprint generator 722, whichcan be configured to generate a service fingerprint 707. The servicefingerprint generator 722 can be configured to generate a servicefingerprint including information associated with the SSL certificate ofthe server 709. In some implementations, the service fingerprint 707 caninclude information corresponding to the SSL certificate (or the SSLcertificate itself) of the respective virtual server of the server 709,one or more domain name service (DNS) aliases for a virtual IP addressof the respective virtual server, one or more port numbers serving theSSL certificate, and an IP address associated with the respectivevirtual server, such as an IP address serviced by the device 705. Insome implementations, the IP address serviced by the device can be an IPaddress of a server corresponding to the virtual server. In someimplementations, the service fingerprint 707 does not includeinformation corresponding to the private key of the server 709. Theinformation included in the service fingerprint 707 can later be used toverify the authenticity of connections established between agents 715and a server that purports to be the server 709, as discussed furtherbelow. In some implementations, the service fingerprint 707 generated bythe service fingerprint generator 722 can be or can include a computerfile storing information in text format. In some other implementations,the service fingerprint 707 can include a package having two or morecomputer files.

In some implementations, the service fingerprint generator 722 can beconfigured to generate the service fingerprint 707 in response to adetected configuration change of a virtual server of the device 705. Aconfiguration change can be detected, for example, by the configurationchange identifier 720. In some implementations, the configuration changeidentifier 720 can detect a configuration change by determining that theSSL certificate of the virtual server has replaced an expired SSLcertificate of the virtual server. In some other implementations, theconfiguration change identifier 720 can detect a configuration change bydetermining that the virtual server is associated with a new IP addressthat was not previously serviced by the virtual server. In still otherimplementations, the configuration change identifier 720 can detect aconfiguration change by determining that the virtual server services anew DNS name not previously serviced by the virtual server.

The device 705 can include the service fingerprint transmitter 726,which can be configured to send or transmit the service fingerprint 707of the server 709 to the web service 710. In some implementations, theservice fingerprint transmitter 726 retrieves a service fingerprint 707from the service fingerprint generator 722, and subsequently transmitsthe service fingerprint 707 to the web service 710. In someimplementations, the web service 710 can maintain a record of theservice fingerprint 707 received from the device 705. For example, theservice fingerprint 707 can be stored in a database maintained by theweb service 710. In some implementations, the web service 710 can storea plurality of service fingerprints 707 received from the device 705, aswell as any other devices that may send service fingerprints similar tothe service fingerprint 707 to the web service 710.

In some implementations, the web service 710 can use the informationincluded in all of its stored service fingerprints 707 to create aservice mapping of SSL certificates and virtual servers. For example,based on the service fingerprints 707, the web service 710 can determinethat a particular SSL certificate is associated with a particularvirtual server of the device 705. In some implementations, an SSLcertificate may be associated with more than one virtual server. In someimplementations, the web service can combine the service fingerprintsreceived from one or more devices owned by a customer (or server owner)to construct a full set of mappings for which the certificate should beissued by any particular Internet-facing virtual server.

For example, there may be two or more servers 709 each configured tostore the same SSL certificate. Each of the servers 709 may have acorresponding virtual server on the device 705. Thus, the web service710 can determine that the SSL certificate could be issued from any ofthe virtual servers associated with that SSL certificate on the device705. The service mapping maintained by the web service 710 can bestored, for example, in a database. The web service 710 can improve thesecurity of SSL connections to the server 709 by using the servicemapping to detect potential attacks, such as MITM attacks, by thirdparties who may be attempting to intercept the data communicated throughthe SSL connections.

The web service 710 can be configured to deploy a plurality of agents715 on computing devices across geographically disparate locations. Theagents 715 can execute on one or more computing devices. The agents 715can be configured to attempt to establish an SSL connection to thevirtual server corresponding to the server 709. The web service 710 cansend instructions to one or more agents to establish a secure connectionwith one or more virtual servers. In some implementations, the agentscan be configured to establish secure connections according to one ormore policies. The policies can include one or more rules according towhich the agents can attempt to establish secure connections. Forexample, in some implementations, the agents 715 can be configured toestablish connections with a subset of servers, such as the server 709,based on a location of the servers, for example, relative to thelocation of the device on which the agent is executing. In someimplementations, the agents 715 can be configured to establish secureconnections with various servers based on a time of day. In someimplementations, the agents 715 can be provided a list of one or moreservers with which to establish a secure connection.

When one or more agents 715 request a secure connection, such requestscan be received, for example, by the secure connection interface 724 ofthe device 705 as shown in FIG. 7B. After the device 705 receives arequest to establish the secure connection between the virtual serverand the agents 715, the device 705 can respond by issuing thecorresponding SSL certificate to each of the respective requestingagents 715. The SSL certificate can be transmitted to the agents 715 viathe secure connection interface 724. The agents 715 can then communicateinformation to the web service 710 corresponding to the issued SSLcertificate and the IP address from which the SSL certificate wasreceived.

The web service 710 can compare the information received from the agents715 to the service mapping maintained by the web service 710. Asdiscussed above, the web service 710 can use the information included inthe service mapping to determine which virtual server should be issuinga given SSL certificate to an agent 715 that requests a secureconnection to the virtual server. Thus, the web service 710 can detectthat a virtual server may be compromised by determining a mismatchbetween information extracted from packets received from the agents 715,such as the source IP address, and the IP address included in theservice mapping. The web service 710 also can detect that a virtualserver may be compromised by determining a mismatch between an SSLcertificate received from an agent 715 and the SSL certificate includedin the service mapping. For example, if the web service 710 detects thatthe SSL certificate received by an agent 715 does not match the expectedSSL certificate included in the service mapping, the web service 710 candetermine that the SSL certificate received by the agent 715 was likelyforged.

Conversely, if the web service 710 detects that the SSL certificatereceived by the agent matches the expected SSL certificate, but the IPaddress from which the SSL certificate was received does not match theIP address (or a DNS alias of the IP address) included in the servicemapping, the web service 710 can determine that the server issuing theSSL certificate is different from the server 709, indicating that theendpoint of the SSL connection may an untrusted server, rather than theserver 709. Therefore, when the web service 710 determines a mismatchbetween the information received from the agents 715 and the informationincluded in the service mapping, the web service 710 can notify theowner of the server 709 that the server 709 may be under attack by athird party. In some implementations, such a notification can betransmitted to and received by the notification receiver 730 of thedevice 705.

In some implementations, the web service 710 can generate a notificationin text format. For example, the notification can include human readabletext configured to be displayed by the device 705 after the device 705receives the notification from the web service 710. In someimplementations, such text may include an indication of the type ofattack that the web service 710 determined, such as a MITM attack. Thenotification also may include information relating to the SSLcertificate that caused the notification to be generated, or the port orIP address from which the SSL certificate was received. In some otherimplementations, the notification may not include human readable text.For example, the web service 710 can generate an encoded notificationand can transmit the encoded notification to the device 705. The device705 can then be configured to decode the notification to determinedetails about the attack that the web service 710 detected, such as theSSL certificates, ports, and IP addresses associated with the attack.

In some implementations, the agents 715 may be geographicallydistributed. For example, some SSL attacks may only impact SSLconnections to the server 709 that originate in a particular serviceprovider network. Agents 715 deployed or otherwise located outside ofthe affected service provider network may not detect the potentialthreat. Thus, deploying or distributing agents 715 across many differentservice provider networks in a wide range of geographic locations canimprove the reliability with which potential attacks on the server 709are detected.

In some implementations, the device 705 may generate a uniqueverification key that can be included in the service fingerprint 707.For example, the unique verification key can be generated by theverification key generator 728 of the device 705, as shown in FIG. 7B.In some implementations, the verification key can be a unique series ofletters and numbers that can be generated by the verification keygenerator 728 in a random or pseudorandom manner for security purposes.In some other implementations, the verification key can be a uniquestring of bits. In still other implementations, the verification key canbe one or more computer files. In yet other implementations, theverification key can have the same format as an SSL private key. In someimplementations, the verification key can be transmitted can betransmitted to an agent 715 when the agent 715 issues a request toestablish a secure connection. In some implementations, the verificationkey can be transmitted to the agent 715 via the secure connectioninterface 724. This verification key can then be checked by the agents715 via a private extension to the SSL handshake to enable greaterconfidence that the SSL endpoint is in fact the server 709. In someimplementations, the agents 715 may collect additional informationrelevant to understanding the nature of a potential attack. For example,the output of a “traceroute” command performed on data transmitted overan established SSL connection can provide additional informationregarding the likely connection path affected by an attack. In someimplementations, the web service 710 may collect feeds of SSLcertificates issued or revoked from certificate authorities as anadditional source indicating whether the SSL certificate of the server709 has been compromised. In some implementations, the web service 710may monitor additional protocols, such as the border gateway protocol(BGP), to detect whether the virtual server corresponding to the server709 has been compromised by a malicious traffic route. In someimplementations, the web service 710 may periodically check all knowncertificates against evolving industry best practices, such as keylength, padding, and crypto algorithms, to determine whether an SSLcertificate no longer follows up-to-date best practices.

FIG. 7C is a flow chart of an embodiment of a method for improvingsecurity of SSL communications. In brief overview, the method 750includes generating one or more service fingerprints for one or morevirtual servers (step 755). The method 750 includes creating a servicemapping of SSL certificates and virtual servers based on the one or moreservice fingerprints (step 760). The method 750 further includesestablishing an SSL connection to at least one of the virtual servers toreceive an SSL certificate (step 765). The method 750 also includesdetermining that the at least one virtual server is compromised based ona mismatch between the respective service mapping of the at least onevirtual server and the received SSL certificate or the IP address fromwhich the SSL certificate was received (step 770).

Referring again to FIG. 7C, and in greater detail, a service fingerprintgenerator of a device intermediary to one or more clients and one ormore servers can generate one or more service fingerprints for one ormore virtual servers (step 755). Each of the virtual servers can beexecuted by the device and can correspond to a respective one of theservers. Each service fingerprint can include information correspondingto an SSL certificate of the respective virtual server, DNS aliases fora virtual IP address of the respective virtual server, a port numberserving the SSL certificate, and an IP address associated with therespective virtual server, such as an IP address serviced by the device705. In some implementations, the IP address serviced by the device canbe an IP address of a server corresponding to the virtual server. Insome implementations, the intermediary device on which the servicefingerprint generator executes can be connected to a physical serverthat is configured to issue SSL certificates. The device can include avirtual server corresponding to the physical server, such that the SSLcertificates issued by the physical server are transmitted through thedevice in response to a request from an external client device toestablish a secure connection. In some implementations, the device cantransmit the service fingerprint to a web service.

The web service can create a service mapping of SSL certificates andvirtual servers, based on the one or more service fingerprints (step760). For example, based on the service fingerprints received from theintermediary device, the web service can determine that a particular SSLcertificate is associated with a particular virtual server. In someimplementations, an SSL certificate may be associated with more than onevirtual server. Thus, the web service can determine that the SSLcertificate could be issued to an external device from any of thevirtual servers associated with that SSL certificate.

An agent can establish an SSL connection to at least one of the virtualservers to receive an SSL certificate (step 765). In someimplementations, the SSL connection can be established by the agent byentering a uniform resource locator (URL) associated with the virtualserver into a web browser application of the agent. In response to theattempt to establish a connection to the virtual server, the agent canreceive an SSL certificate. In some implementations, the agent canestablish more than one connection to the virtual server. For example,agents located in different service provider networks of variousgeographic regions can each establish respective connections to thevirtual server. Each agent that attempts to establish a secureconnection to the virtual server can receive an SSL certificate inresponse. Each agent also can transmit the received SSL certificate tothe web service. In some implementations, each agent also can submitother information to the web service, such as the IP address or portnumber from which the SSL certificate was received.

The web service can determine that the at least one virtual server iscompromised, based on a mismatch between the respective service mappingof the at least one virtual server and the received SSL certificate orthe IP address from which the SSL certificate was received (step 760).The web service can use the information included in the service mappingto determine which virtual server should be issuing a given SSLcertificate. For example, the web service can refer to the servicefingerprint of a given SSL certificate to determine that the virtualserver that is associated with that SSL certificate. Therefore, if theweb service determines that the received SSL certificate does not matchthe expected SSL certificate included in the service mapping, the webservice also can determine that the received SSL certificate may havebeen forged. Similarly, if the web service determines that the receivedSSL certificate matches the expected SSL certificate, but the IP addressfrom which the SSL certificate was received does not match the IPaddress or a DNS alias of the IP address included in the servicemapping, the web service also can determine that the server issuing theSSL certificate is different from the expected server. This may indicatethat the endpoint of the SSL connection is an untrusted server, ratherthan the expected server.

FIG. 7D is a flow chart of an embodiment of a second method 780 forimproving security of SSL communications. In brief overview, the method780 can include determining, by a device intermediary to a plurality ofclients and one or more servers, a configuration change associated witha virtual server executing on the device (step 785). The method caninclude generating, by the device, responsive to determining theconfiguration change associated with the virtual server, a servicefingerprint for the virtual server (step 790). The service fingerprintcan include a DNS alias for a virtual IP address of the virtual server,a port number of the virtual server serving an SSL certificate of thevirtual server, an IP address of the virtual server, and the SSLcertificate. The method can include transmitting, by the device, thegenerated service fingerprint to a web service to compare the generatedservice fingerprint with data received by the web service from an agentto identify that the device is under attack (step 795).

Referring again to FIG. 7D, and in greater detail, the method 780 caninclude determining, by a device intermediary to a plurality of clientsand one or more servers, a configuration change associated with avirtual server executing on the device (step 785). In someimplementations, a configuration change identifier of the device, suchas the configuration change identifier 720 shown in FIG. 7B, can detecta configuration change. The configuration change identifier can detect aconfiguration change by determining that the SSL certificate of thevirtual server has replaced an expired SSL certificate of the virtualserver. In some other implementations, the configuration changeidentifier can detect a configuration change by determining that thevirtual server is associated with a new IP address that was notpreviously serviced by the virtual server. In still otherimplementations, the configuration change identifier can detect aconfiguration change by determining that the virtual server services anew DNS name not previously serviced by the virtual server.

The method can include generating, by the device, responsive todetermining the configuration change associated with the virtual server,a service fingerprint for the virtual server (step 790). The servicefingerprint can include a DNS alias for a virtual IP address of thevirtual server, a port number of the virtual server serving an SSLcertificate of the virtual server, an IP address of the virtual server,and the SSL certificate. In some implementations, a service fingerprintgenerator of the device, such as the service fingerprint generator 722shown in FIG. 7B, can be configured to generate the service fingerprint.In some implementations, the service fingerprint can include the SSLcertificate of the virtual server, one or more DNS aliases for a virtualIP address of the virtual server, a port number serving the SSLcertificate, and an IP address associated with the respective virtualserver. In some implementations, the service fingerprint does notinclude information corresponding to the private key of the server. Aremote web service can receive the service fingerprint and can later usethe information included in the service fingerprint to verify theauthenticity of connections established between agents and the virtualserver. In some implementations, the service fingerprint generated bythe service fingerprint generator can be or can include a computer filestoring information in text format. In some other implementations, theservice fingerprint can include a package having two or more computerfiles.

The method can include transmitting, by the device, the generatedservice fingerprint to a web service to compare the generated servicefingerprint with data received by the web service from an agent toidentify that the device is under attack (step 795). In someimplementations, a service fingerprint transmitter of the device, suchas the service fingerprint transmitter 726 shown in FIG. 7B, cantransmit the service fingerprint to the web service. In someimplementations, the service fingerprint transmitter retrieves theservice fingerprint from the service fingerprint generator, andsubsequently transmits the service fingerprint to the web service. Insome implementations, the web service can maintain a record of theservice fingerprint received from the device. For example, the webservice can maintain a database and can store the fingerprint in thedatabase. In some implementations, the web service can store a pluralityof service fingerprints received from the device, as well as any otherdevices that may send service fingerprints similar to the servicefingerprint to the web service.

It should be understood that the systems described above may providemultiple ones of any or each of those components and these componentsmay be provided on either a standalone machine or, in some embodiments,on multiple machines in a distributed system. The systems and methodsdescribed above may be implemented as a method, apparatus or article ofmanufacture using programming and/or engineering techniques to producesoftware, firmware, hardware, or any combination thereof. In addition,the systems and methods described above may be provided as one or morecomputer-readable programs embodied on or in one or more articles ofmanufacture. The term “article of manufacture” as used herein isintended to encompass code or logic accessible from and embedded in oneor more computer-readable devices, firmware, programmable logic, memorydevices (e.g., EEPROMs, ROMs, PROMs, RAMs, SRAMs, etc.), hardware (e.g.,integrated circuit chip, Field Programmable Gate Array (FPGA),Application Specific Integrated Circuit (ASIC), etc.), electronicdevices, a computer readable non-volatile storage unit (e.g., CD-ROM,floppy disk, hard disk drive, etc.). The article of manufacture may beaccessible from a file server providing access to the computer-readableprograms via a network transmission line, wireless transmission media,signals propagating through space, radio waves, infrared signals, etc.The article of manufacture may be a flash memory card or a magnetictape. The article of manufacture includes hardware logic as well assoftware or programmable code embedded in a computer readable mediumthat is executed by a processor. In general, the computer-readableprograms may be implemented in any programming language, such as LISP,PERL, C, C++, C#, PROLOG, or in any byte code language such as JAVA. Thesoftware programs may be stored on or in one or more articles ofmanufacture as object code.

While various embodiments of the methods and systems have beendescribed, these embodiments are exemplary and in no way limit the scopeof the described methods or systems. Those having skill in the relevantart can effect changes to form and details of the described methods andsystems without departing from the broadest scope of the describedmethods and systems. Thus, the scope of the methods and systemsdescribed herein should not be limited by any of the exemplaryembodiments and should be defined in accordance with the accompanyingclaims and their equivalents.

What is claimed is:
 1. A method comprising: identifying, by a deviceintermediary to a plurality of clients and one or more servers, a changein configuration of the device; generating, by the device responsive toidentifying the change in configuration, a fingerprint comprising a portnumber of the device serving a secure socket layer (SSL) certificate,and internet protocol (IP) address of the device and the SSLCertificate; communicating, by the device, the fingerprint to a servicethat identifies whether the device is under attack based at least oncomparing the fingerprint to information of a mapping of the SSLcertificate to the device; and receiving, by the device responsive tocommunicating the fingerprint, a communication from the service that thedevice is under attack.
 2. The method of claim 1, further comprisingidentifying, by the device, the change in configuration of a virtualserver of the device that manages network traffic between the pluralityof clients and the one or more servers.
 3. The method of claim 2,further comprising generating, by the device, the fingerprint to includethe IP address of the virtual server.
 4. The method of claim 3, whereinthe fingerprint comprises a domain name service identifier for the IPaddress of the virtual server.
 5. The method of claim 1, furthercomprising identifying, by the device, the change in configurationcomprising a change in the SSL certificate of the device.
 6. The methodof claim 1, further comprising identifying, by the device, the change inconfiguration comprising a change in a domain name service name for theSSL certificate.
 7. The method of claim 1, wherein the device receivesfrom the service the communication identifying a type of the attack. 8.The method of claim 1, wherein the service determines that there is amismatch between the fingerprint and the mapping of the SSL certificateto the device.
 9. The method of claim 1, wherein the service obtainsdata, from one or more agents, the one or more agents configured toestablish an SSL connection with at least the device.
 10. The method ofclaim 9, wherein the service obtains data, from the one or more agents,that identifies the SSL certificate issued by the device to the agentand the IP address from which the SSL certificate was received by theone or more agents.
 11. A system comprising: a device comprising one ormore processors, coupled to memory and intermediary to a plurality ofclients and one or more servers, the device configured to: identify achange in configuration of the device; generate, responsive toidentifying the change in configuration, a fingerprint comprising a portnumber of the device serving a secure socket layer (SSL) certificate,and interne protocol (IP) address of the device and the SSL Certificate;communicate the fingerprint to a service that identifies whether thedevice is under attack based at least on comparing the fingerprint toinformation of a mapping of the SSL certificate to the device; andreceive, responsive to communicating the fingerprint, a communicationfrom the service that the device is under attack.
 12. The system ofclaim 11, wherein the device is further configured to identify thechange in configuration of a virtual server of the device that managesnetwork traffic between the plurality of clients and the one or moreservers.
 13. The system of claim 12, wherein the device is furtherconfigured to generate the fingerprint to include the IP address of thevirtual server.
 14. The system of claim 13, wherein the fingerprintcomprises a domain name service identifier for the IP address of thevirtual server.
 15. The system of claim 11, wherein the device isfurther configured to identify the change in configuration comprising achange in the SSL certificate of the device.
 16. The system of claim 11,wherein the device is further configured to identify the change inconfiguration comprising a change in a domain name service name for theSSL certificate.
 17. The system of claim 11, wherein the device isfurther configured to receive from the service the communicationidentifying a type of the attack.
 18. The system of claim 11, whereinthe service is further configured to determine that there is a mismatchbetween the fingerprint and the mapping of the SSL certificate to thedevice.
 19. The system of claim 11, wherein the service is furtherconfigured to obtain data, from one or more agents, the one or moreagents configured to establish an SSL connection with at least thedevice.
 20. The system of claim 19, wherein the service is furtherconfigured to obtain data, from the one or more agents, that identifiesthe SSL certificate issued by the device to the agent and the IP addressfrom which the SSL certificate was received by the one or more agents.